INTRODUCTION — Hypoglycemia, also known as low blood sugar, occurs when levels of glucose (sugar) in the blood are too low. Hypoglycemia is common in people with diabetes who take insulin or oral medications that cause insulin secretion. People with type 2 diabetes often use diet control or oral medications that do not cause insulin secretion; hypoglycemia does not occur in these patients.
Hypoglycemia happens when a person with diabetes does one or more of the following: Takes too much insulin (or drugs that cause insulin secretion) Does not eat enough food Exercises vigorously without eating a snack or decreasing the dose of insulin beforehand Waits too long between meals Drinks excessive alcohol, although even moderate alcohol use can increase the risk of hypoglycemia in patients with type 1 diabetes
SYMPTOMS — The symptoms of hypoglycemia vary from person to person, and can change over time. Patients who drink excessive amounts of alcohol, are tired, or who take beta-blocking medications may not notice their symptoms, or may not recognize that the symptoms are due to hypoglycemia.
During the early stages of a hypoglycemic episode, symptoms may include: Sweating Tremor Hunger Anxiety
If untreated, symptoms can become more severe, and can include: Lack of coordination Weakness Lethargy Blurred vision Bizarre behavior or personality change Confusion Unconsciousness or seizure
When possible, hypoglycemia should be confirmed by measuring the blood glucose level. (See "Patient information: Self-blood glucose monitoring"). A blood glucose below 60 mg/dL, in the presence of symptoms, indicates hypoglycemia for most patients.
Some patients with diabetes can experience hypoglycemia at slightly higher blood glucose levels. Patients whose blood glucose levels are high for long periods of time may have symptoms of low blood glucose and feel poorly when levels approach 100 mg/dL. These patients should intensify their diabetic regimen to get blood glucose levels into a range that is closer to normal. This will lower the blood glucose level at which a patient feels symptoms.
Hypoglycemia unawareness — Hypoglycemia unawareness occurs when a person does not have the early symptoms of low blood glucose. As a result, the person cannot respond in the early stages, and severe signs of hypoglycemia, such as loss of consciousness or seizures, are more likely. It is a common occurrence, especially in patients who have had type 1 diabetes for greater than five to 10 years.
Hypoglycemia and hypoglycemia unawareness occur more frequently in patients who tightly control their blood glucose levels with insulin (called intensive therapy, show figure 1). Frequent low blood glucose levels reduce the production of the hormones which produce symptoms of low blood glucose.
Hypoglycemia unawareness can also occur in patients who take medications that stimulate insulin secretion (for example Micronase® [glyburide]), especially if they are elderly or have impaired kidney or heart function who take an oral medication that stimulates insulin secretion (show figure 2).
Nocturnal hypoglycemia — Low blood glucose that occurs when a person is sleeping (nocturnal hypoglycemia) can disrupt sleep and often goes unrecognized. Nocturnal hypoglycemia is a form of hypoglycemia unawareness. Thus, a person with nocturnal hypoglycemia is less likely to have symptoms that alert them to the need for treatment. Nocturnal hypoglycemia can be difficult to diagnose, and can increase the risk of hypoglycemia unawareness in the 48 to 72 hours that follow.
PREVENTION — The best way to prevent hypoglycemia is to monitor blood glucose levels frequently and be prepared at all times to treat it promptly. The patient as well as a close friend or relative need to learn the symptoms, and patients at risk for hypoglycemia (those treated with insulin and some oral medications, show figure 2) should always carry glucose tablets, hard candy, or other sources of fast-acting carbohydrate. Glucose tablets are recommended since they have a pleasant taste, but are not likely to be eaten for reasons other than hypoglycemia. Candy can be tempting to eat, even when blood glucose levels are normal, especially for children with diabetes.
Hypoglycemia can be frightening and unpleasant, and it is common for patients who have experienced an episode of severe hypoglycemia to be fearful of future episodes. Patients who experience this fear may keep their blood glucose excessively high, which can lead to long term complications.
It may be helpful to discuss fears of hypoglycemia with a healthcare provider. In addition, patients should ask about blood glucose awareness education and training in the use of glucagon, an injectable drug that raises blood sugar levels quickly. Blood glucose awareness training can improve a patient's ability to recognize low blood glucose earlier, which may help to prevent episodes of severe hypoglycemia.
TREATMENT — While the blood glucose level should be tested as soon as possible, treatment should not be delayed if monitoring equipment (blood glucose meter, test strips, lancet) is not readily available. Treatment of hypoglycemia should be quick, especially if blood glucose levels are less than 40 mg/dL.
As soon as symptoms are noted, a patient should eat 10 to 15 grams of fast-acting carbohydrate. Examples include: Three to four glucose tablets Six to eight hard candies 1/2 cup fruit juice
This amount of food is usually enough to raise the blood glucose into a safe range without causing high blood glucose levels (called hyperglycemia). Foods that contain fat (like candy bars) or protein (cheese) should initially be avoided, since they slow down the body's ability to absorb glucose.
After 15 minutes, the blood glucose level should be measured again. It is important to wait since it takes time for the body to absorb glucose and for symptoms to resolve. If the blood glucose level is below 60 mg/dL, or if symptoms persist, another 10 to 15 grams of fast-acting carbohydrate should be eaten.
Once symptoms and blood glucose levels are under control, a snack may be needed to control blood glucose levels until the next meal. If the next meal is more than one hour away or the patient has just completed vigorous exercise, a snack including 15 grams of carbohydrate and 1 ounce of protein should be eaten. Examples of this include crackers with cheese or one-half of a sandwich with peanut butter. It is important not to eat too much, as this can raise blood glucose levels above the target level.
Glucagon — If hypoglycemia is severe, the patient may become unconscious or unable to eat. A close friend or relative should be trained to recognize severe hypoglycemia and treat it quickly. Dealing with a loved one who is pale, sweaty, acting in a bizarre way, or unconscious and convulsing can be scary. An injection of glucagon stops these symptoms quickly.
Glucagon is a hormone that raises blood glucose levels. Glucagon is available in emergency kits, which can be bought with a prescription in a pharmacy (show picture 1). Directions are included in each kit; a roommate, spouse, or parent should familiarize themselves with the injection procedure before an emergency occurs.
It is important that the glucagon kit is easy to locate, is not expired, and that the friend or relative is able to stay calm. It is important that the kit is refilled when the expiration date approaches, though administering an expired kit is unlikely to cause harm.
Procedure — Glucagon is injected subcutaneously (under the skin) of the thigh or abdomen. The injection sites and technique are similar to an insulin injection. Remove the needle protector and inject the entire content of the syringe (a clear solution) into the glucagon powder. Do not remove the plastic clip on the syringe. Remove syringe from the bottle. Swirl the mixture gently until the powder is dissolved. The solution should be clear. Do not use the solution if it is discolored. Hold the bottle upside down and withdraw the contents into the syringe (1 mg mark on syringe for adults and children over 44 pounds [20 kilograms]). Children under 44 pounds need one-half the dose, and only 1/2 the solution should be withdrawn (0.5 mg mark on syringe). Cleanse the injection site (abdomen or thigh) with an alcohol swab (show figure 3) Insert the needle into the skin (show picture 2). Press the plunger to inject the glucagon. Withdraw the needle, and replace the syringe in the storage case (do not attempt to re-cap the needle). Press lightly at the injection site. Turn the patient to his or her side. This prevents choking if the patient vomits.
Symptoms should resolve within 10 to 15 minutes, although nausea and vomiting may follow 60 to 90 minutes later. As soon as the patient is awake and able to swallow, a fast-acting carbohydrate such as glucose tablets or juice should be offered. After the patient begins to feel better, he or she should eat a snack with protein, such as crackers and cheese or a peanut butter sandwich.
If the patient is not conscious within 10 minutes, another glucagon injection should be given, if a second kit is available. Emergency help should be called immediately.
WHEN TO SEEK HELP — A family member or friend should take a patient to the hospital or call for emergency assistance (911 in many US communities) immediately if the patient: Remains confused or in an altered mental state after being treated with glucagon Is unconscious (or nearly unconscious) and glucagon is not available Continues to have low blood glucose despite eating adequate amounts of a fast-acting carbohydrate or receiving glucagon
Once in a hospital or ambulance, intravenous glucose is given to raise levels immediately.
FOLLOW UP CARE — After the blood glucose level is normal and symptoms are gone, a patient can usually resume his or her normal activities. A patient who required glucagon should speak with his or her healthcare provider. This can help to identify the cause of a severely low blood glucose level, and adjustments can be made to prevent future reactions. Patients who require emergency care may be observed for a few hours before being released. A friend or relative should drive the patient home.
Patients should be especially careful in the first 48 to 72 hours after a hypoglycemic episode, because his or her ability to recognize the symptoms of low blood glucose may be impaired. In addition, the body's ability to counteract low blood glucose levels is decreased.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes & Digestive & Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-4]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Cox, DJ, Gonder-Frederick, L, Julian, DM, Clarke, W. Long-term follow-up evaluation of blood glucose awareness training. Diabetes Care 1994; 17:1.
2. Fanelli, CG, Paramore, DS, Hershey, T, et al. Impact of nocturnal hypoglycemia on hypoglycemic cognitive dysfunction in type 1 diabetes. Diabetes 1998; 47:1920.
3. Irvine, AA, Cox, D. Gonder-Frederick, L. Fear of hypoglycemia: Relationship to physical symptoms in patients with insulin-dependent diabetes. Health Psych 1992; 11:135.
4. Weinger, K, Kinsley, BT, Levy, CJ, et al. The perception of safe driving ability during hypoglycemia in patients with type 1 diabetes mellitus. Am J Med 1999; 107:246.
Tuesday, October 16, 2007
Hypoglycemia (low blood glucose) in diabetes
INTRODUCTION — Hypoglycemia, also known as low blood sugar, occurs when levels of glucose (sugar) in the blood are too low. Hypoglycemia is common in people with diabetes who take insulin or oral medications that cause insulin secretion. People with type 2 diabetes often use diet control or oral medications that do not cause insulin secretion; hypoglycemia does not occur in these patients.
Hypoglycemia happens when a person with diabetes does one or more of the following: Takes too much insulin (or drugs that cause insulin secretion) Does not eat enough food Exercises vigorously without eating a snack or decreasing the dose of insulin beforehand Waits too long between meals Drinks excessive alcohol, although even moderate alcohol use can increase the risk of hypoglycemia in patients with type 1 diabetes
SYMPTOMS — The symptoms of hypoglycemia vary from person to person, and can change over time. Patients who drink excessive amounts of alcohol, are tired, or who take beta-blocking medications may not notice their symptoms, or may not recognize that the symptoms are due to hypoglycemia.
During the early stages of a hypoglycemic episode, symptoms may include: Sweating Tremor Hunger Anxiety
If untreated, symptoms can become more severe, and can include: Lack of coordination Weakness Lethargy Blurred vision Bizarre behavior or personality change Confusion Unconsciousness or seizure
When possible, hypoglycemia should be confirmed by measuring the blood glucose level. (See "Patient information: Self-blood glucose monitoring"). A blood glucose below 60 mg/dL, in the presence of symptoms, indicates hypoglycemia for most patients.
Some patients with diabetes can experience hypoglycemia at slightly higher blood glucose levels. Patients whose blood glucose levels are high for long periods of time may have symptoms of low blood glucose and feel poorly when levels approach 100 mg/dL. These patients should intensify their diabetic regimen to get blood glucose levels into a range that is closer to normal. This will lower the blood glucose level at which a patient feels symptoms.
Hypoglycemia unawareness — Hypoglycemia unawareness occurs when a person does not have the early symptoms of low blood glucose. As a result, the person cannot respond in the early stages, and severe signs of hypoglycemia, such as loss of consciousness or seizures, are more likely. It is a common occurrence, especially in patients who have had type 1 diabetes for greater than five to 10 years.
Hypoglycemia and hypoglycemia unawareness occur more frequently in patients who tightly control their blood glucose levels with insulin (called intensive therapy, show figure 1). Frequent low blood glucose levels reduce the production of the hormones which produce symptoms of low blood glucose.
Hypoglycemia unawareness can also occur in patients who take medications that stimulate insulin secretion (for example Micronase® [glyburide]), especially if they are elderly or have impaired kidney or heart function who take an oral medication that stimulates insulin secretion (show figure 2).
Nocturnal hypoglycemia — Low blood glucose that occurs when a person is sleeping (nocturnal hypoglycemia) can disrupt sleep and often goes unrecognized. Nocturnal hypoglycemia is a form of hypoglycemia unawareness. Thus, a person with nocturnal hypoglycemia is less likely to have symptoms that alert them to the need for treatment. Nocturnal hypoglycemia can be difficult to diagnose, and can increase the risk of hypoglycemia unawareness in the 48 to 72 hours that follow.
PREVENTION — The best way to prevent hypoglycemia is to monitor blood glucose levels frequently and be prepared at all times to treat it promptly. The patient as well as a close friend or relative need to learn the symptoms, and patients at risk for hypoglycemia (those treated with insulin and some oral medications, show figure 2) should always carry glucose tablets, hard candy, or other sources of fast-acting carbohydrate. Glucose tablets are recommended since they have a pleasant taste, but are not likely to be eaten for reasons other than hypoglycemia. Candy can be tempting to eat, even when blood glucose levels are normal, especially for children with diabetes.
Hypoglycemia can be frightening and unpleasant, and it is common for patients who have experienced an episode of severe hypoglycemia to be fearful of future episodes. Patients who experience this fear may keep their blood glucose excessively high, which can lead to long term complications.
It may be helpful to discuss fears of hypoglycemia with a healthcare provider. In addition, patients should ask about blood glucose awareness education and training in the use of glucagon, an injectable drug that raises blood sugar levels quickly. Blood glucose awareness training can improve a patient's ability to recognize low blood glucose earlier, which may help to prevent episodes of severe hypoglycemia.
TREATMENT — While the blood glucose level should be tested as soon as possible, treatment should not be delayed if monitoring equipment (blood glucose meter, test strips, lancet) is not readily available. Treatment of hypoglycemia should be quick, especially if blood glucose levels are less than 40 mg/dL.
As soon as symptoms are noted, a patient should eat 10 to 15 grams of fast-acting carbohydrate. Examples include: Three to four glucose tablets Six to eight hard candies 1/2 cup fruit juice
This amount of food is usually enough to raise the blood glucose into a safe range without causing high blood glucose levels (called hyperglycemia). Foods that contain fat (like candy bars) or protein (cheese) should initially be avoided, since they slow down the body's ability to absorb glucose.
After 15 minutes, the blood glucose level should be measured again. It is important to wait since it takes time for the body to absorb glucose and for symptoms to resolve. If the blood glucose level is below 60 mg/dL, or if symptoms persist, another 10 to 15 grams of fast-acting carbohydrate should be eaten.
Once symptoms and blood glucose levels are under control, a snack may be needed to control blood glucose levels until the next meal. If the next meal is more than one hour away or the patient has just completed vigorous exercise, a snack including 15 grams of carbohydrate and 1 ounce of protein should be eaten. Examples of this include crackers with cheese or one-half of a sandwich with peanut butter. It is important not to eat too much, as this can raise blood glucose levels above the target level.
Glucagon — If hypoglycemia is severe, the patient may become unconscious or unable to eat. A close friend or relative should be trained to recognize severe hypoglycemia and treat it quickly. Dealing with a loved one who is pale, sweaty, acting in a bizarre way, or unconscious and convulsing can be scary. An injection of glucagon stops these symptoms quickly.
Glucagon is a hormone that raises blood glucose levels. Glucagon is available in emergency kits, which can be bought with a prescription in a pharmacy (show picture 1). Directions are included in each kit; a roommate, spouse, or parent should familiarize themselves with the injection procedure before an emergency occurs.
It is important that the glucagon kit is easy to locate, is not expired, and that the friend or relative is able to stay calm. It is important that the kit is refilled when the expiration date approaches, though administering an expired kit is unlikely to cause harm.
Procedure — Glucagon is injected subcutaneously (under the skin) of the thigh or abdomen. The injection sites and technique are similar to an insulin injection. Remove the needle protector and inject the entire content of the syringe (a clear solution) into the glucagon powder. Do not remove the plastic clip on the syringe. Remove syringe from the bottle. Swirl the mixture gently until the powder is dissolved. The solution should be clear. Do not use the solution if it is discolored. Hold the bottle upside down and withdraw the contents into the syringe (1 mg mark on syringe for adults and children over 44 pounds [20 kilograms]). Children under 44 pounds need one-half the dose, and only 1/2 the solution should be withdrawn (0.5 mg mark on syringe). Cleanse the injection site (abdomen or thigh) with an alcohol swab (show figure 3) Insert the needle into the skin (show picture 2). Press the plunger to inject the glucagon. Withdraw the needle, and replace the syringe in the storage case (do not attempt to re-cap the needle). Press lightly at the injection site. Turn the patient to his or her side. This prevents choking if the patient vomits.
Symptoms should resolve within 10 to 15 minutes, although nausea and vomiting may follow 60 to 90 minutes later. As soon as the patient is awake and able to swallow, a fast-acting carbohydrate such as glucose tablets or juice should be offered. After the patient begins to feel better, he or she should eat a snack with protein, such as crackers and cheese or a peanut butter sandwich.
If the patient is not conscious within 10 minutes, another glucagon injection should be given, if a second kit is available. Emergency help should be called immediately.
WHEN TO SEEK HELP — A family member or friend should take a patient to the hospital or call for emergency assistance (911 in many US communities) immediately if the patient: Remains confused or in an altered mental state after being treated with glucagon Is unconscious (or nearly unconscious) and glucagon is not available Continues to have low blood glucose despite eating adequate amounts of a fast-acting carbohydrate or receiving glucagon
Once in a hospital or ambulance, intravenous glucose is given to raise levels immediately.
FOLLOW UP CARE — After the blood glucose level is normal and symptoms are gone, a patient can usually resume his or her normal activities. A patient who required glucagon should speak with his or her healthcare provider. This can help to identify the cause of a severely low blood glucose level, and adjustments can be made to prevent future reactions. Patients who require emergency care may be observed for a few hours before being released. A friend or relative should drive the patient home.
Patients should be especially careful in the first 48 to 72 hours after a hypoglycemic episode, because his or her ability to recognize the symptoms of low blood glucose may be impaired. In addition, the body's ability to counteract low blood glucose levels is decreased.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes & Digestive & Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-4]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Cox, DJ, Gonder-Frederick, L, Julian, DM, Clarke, W. Long-term follow-up evaluation of blood glucose awareness training. Diabetes Care 1994; 17:1.
2. Fanelli, CG, Paramore, DS, Hershey, T, et al. Impact of nocturnal hypoglycemia on hypoglycemic cognitive dysfunction in type 1 diabetes. Diabetes 1998; 47:1920.
3. Irvine, AA, Cox, D. Gonder-Frederick, L. Fear of hypoglycemia: Relationship to physical symptoms in patients with insulin-dependent diabetes. Health Psych 1992; 11:135.
4. Weinger, K, Kinsley, BT, Levy, CJ, et al. The perception of safe driving ability during hypoglycemia in patients with type 1 diabetes mellitus. Am J Med 1999; 107:246.
Hypoglycemia happens when a person with diabetes does one or more of the following: Takes too much insulin (or drugs that cause insulin secretion) Does not eat enough food Exercises vigorously without eating a snack or decreasing the dose of insulin beforehand Waits too long between meals Drinks excessive alcohol, although even moderate alcohol use can increase the risk of hypoglycemia in patients with type 1 diabetes
SYMPTOMS — The symptoms of hypoglycemia vary from person to person, and can change over time. Patients who drink excessive amounts of alcohol, are tired, or who take beta-blocking medications may not notice their symptoms, or may not recognize that the symptoms are due to hypoglycemia.
During the early stages of a hypoglycemic episode, symptoms may include: Sweating Tremor Hunger Anxiety
If untreated, symptoms can become more severe, and can include: Lack of coordination Weakness Lethargy Blurred vision Bizarre behavior or personality change Confusion Unconsciousness or seizure
When possible, hypoglycemia should be confirmed by measuring the blood glucose level. (See "Patient information: Self-blood glucose monitoring"). A blood glucose below 60 mg/dL, in the presence of symptoms, indicates hypoglycemia for most patients.
Some patients with diabetes can experience hypoglycemia at slightly higher blood glucose levels. Patients whose blood glucose levels are high for long periods of time may have symptoms of low blood glucose and feel poorly when levels approach 100 mg/dL. These patients should intensify their diabetic regimen to get blood glucose levels into a range that is closer to normal. This will lower the blood glucose level at which a patient feels symptoms.
Hypoglycemia unawareness — Hypoglycemia unawareness occurs when a person does not have the early symptoms of low blood glucose. As a result, the person cannot respond in the early stages, and severe signs of hypoglycemia, such as loss of consciousness or seizures, are more likely. It is a common occurrence, especially in patients who have had type 1 diabetes for greater than five to 10 years.
Hypoglycemia and hypoglycemia unawareness occur more frequently in patients who tightly control their blood glucose levels with insulin (called intensive therapy, show figure 1). Frequent low blood glucose levels reduce the production of the hormones which produce symptoms of low blood glucose.
Hypoglycemia unawareness can also occur in patients who take medications that stimulate insulin secretion (for example Micronase® [glyburide]), especially if they are elderly or have impaired kidney or heart function who take an oral medication that stimulates insulin secretion (show figure 2).
Nocturnal hypoglycemia — Low blood glucose that occurs when a person is sleeping (nocturnal hypoglycemia) can disrupt sleep and often goes unrecognized. Nocturnal hypoglycemia is a form of hypoglycemia unawareness. Thus, a person with nocturnal hypoglycemia is less likely to have symptoms that alert them to the need for treatment. Nocturnal hypoglycemia can be difficult to diagnose, and can increase the risk of hypoglycemia unawareness in the 48 to 72 hours that follow.
PREVENTION — The best way to prevent hypoglycemia is to monitor blood glucose levels frequently and be prepared at all times to treat it promptly. The patient as well as a close friend or relative need to learn the symptoms, and patients at risk for hypoglycemia (those treated with insulin and some oral medications, show figure 2) should always carry glucose tablets, hard candy, or other sources of fast-acting carbohydrate. Glucose tablets are recommended since they have a pleasant taste, but are not likely to be eaten for reasons other than hypoglycemia. Candy can be tempting to eat, even when blood glucose levels are normal, especially for children with diabetes.
Hypoglycemia can be frightening and unpleasant, and it is common for patients who have experienced an episode of severe hypoglycemia to be fearful of future episodes. Patients who experience this fear may keep their blood glucose excessively high, which can lead to long term complications.
It may be helpful to discuss fears of hypoglycemia with a healthcare provider. In addition, patients should ask about blood glucose awareness education and training in the use of glucagon, an injectable drug that raises blood sugar levels quickly. Blood glucose awareness training can improve a patient's ability to recognize low blood glucose earlier, which may help to prevent episodes of severe hypoglycemia.
TREATMENT — While the blood glucose level should be tested as soon as possible, treatment should not be delayed if monitoring equipment (blood glucose meter, test strips, lancet) is not readily available. Treatment of hypoglycemia should be quick, especially if blood glucose levels are less than 40 mg/dL.
As soon as symptoms are noted, a patient should eat 10 to 15 grams of fast-acting carbohydrate. Examples include: Three to four glucose tablets Six to eight hard candies 1/2 cup fruit juice
This amount of food is usually enough to raise the blood glucose into a safe range without causing high blood glucose levels (called hyperglycemia). Foods that contain fat (like candy bars) or protein (cheese) should initially be avoided, since they slow down the body's ability to absorb glucose.
After 15 minutes, the blood glucose level should be measured again. It is important to wait since it takes time for the body to absorb glucose and for symptoms to resolve. If the blood glucose level is below 60 mg/dL, or if symptoms persist, another 10 to 15 grams of fast-acting carbohydrate should be eaten.
Once symptoms and blood glucose levels are under control, a snack may be needed to control blood glucose levels until the next meal. If the next meal is more than one hour away or the patient has just completed vigorous exercise, a snack including 15 grams of carbohydrate and 1 ounce of protein should be eaten. Examples of this include crackers with cheese or one-half of a sandwich with peanut butter. It is important not to eat too much, as this can raise blood glucose levels above the target level.
Glucagon — If hypoglycemia is severe, the patient may become unconscious or unable to eat. A close friend or relative should be trained to recognize severe hypoglycemia and treat it quickly. Dealing with a loved one who is pale, sweaty, acting in a bizarre way, or unconscious and convulsing can be scary. An injection of glucagon stops these symptoms quickly.
Glucagon is a hormone that raises blood glucose levels. Glucagon is available in emergency kits, which can be bought with a prescription in a pharmacy (show picture 1). Directions are included in each kit; a roommate, spouse, or parent should familiarize themselves with the injection procedure before an emergency occurs.
It is important that the glucagon kit is easy to locate, is not expired, and that the friend or relative is able to stay calm. It is important that the kit is refilled when the expiration date approaches, though administering an expired kit is unlikely to cause harm.
Procedure — Glucagon is injected subcutaneously (under the skin) of the thigh or abdomen. The injection sites and technique are similar to an insulin injection. Remove the needle protector and inject the entire content of the syringe (a clear solution) into the glucagon powder. Do not remove the plastic clip on the syringe. Remove syringe from the bottle. Swirl the mixture gently until the powder is dissolved. The solution should be clear. Do not use the solution if it is discolored. Hold the bottle upside down and withdraw the contents into the syringe (1 mg mark on syringe for adults and children over 44 pounds [20 kilograms]). Children under 44 pounds need one-half the dose, and only 1/2 the solution should be withdrawn (0.5 mg mark on syringe). Cleanse the injection site (abdomen or thigh) with an alcohol swab (show figure 3) Insert the needle into the skin (show picture 2). Press the plunger to inject the glucagon. Withdraw the needle, and replace the syringe in the storage case (do not attempt to re-cap the needle). Press lightly at the injection site. Turn the patient to his or her side. This prevents choking if the patient vomits.
Symptoms should resolve within 10 to 15 minutes, although nausea and vomiting may follow 60 to 90 minutes later. As soon as the patient is awake and able to swallow, a fast-acting carbohydrate such as glucose tablets or juice should be offered. After the patient begins to feel better, he or she should eat a snack with protein, such as crackers and cheese or a peanut butter sandwich.
If the patient is not conscious within 10 minutes, another glucagon injection should be given, if a second kit is available. Emergency help should be called immediately.
WHEN TO SEEK HELP — A family member or friend should take a patient to the hospital or call for emergency assistance (911 in many US communities) immediately if the patient: Remains confused or in an altered mental state after being treated with glucagon Is unconscious (or nearly unconscious) and glucagon is not available Continues to have low blood glucose despite eating adequate amounts of a fast-acting carbohydrate or receiving glucagon
Once in a hospital or ambulance, intravenous glucose is given to raise levels immediately.
FOLLOW UP CARE — After the blood glucose level is normal and symptoms are gone, a patient can usually resume his or her normal activities. A patient who required glucagon should speak with his or her healthcare provider. This can help to identify the cause of a severely low blood glucose level, and adjustments can be made to prevent future reactions. Patients who require emergency care may be observed for a few hours before being released. A friend or relative should drive the patient home.
Patients should be especially careful in the first 48 to 72 hours after a hypoglycemic episode, because his or her ability to recognize the symptoms of low blood glucose may be impaired. In addition, the body's ability to counteract low blood glucose levels is decreased.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes & Digestive & Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-4]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Cox, DJ, Gonder-Frederick, L, Julian, DM, Clarke, W. Long-term follow-up evaluation of blood glucose awareness training. Diabetes Care 1994; 17:1.
2. Fanelli, CG, Paramore, DS, Hershey, T, et al. Impact of nocturnal hypoglycemia on hypoglycemic cognitive dysfunction in type 1 diabetes. Diabetes 1998; 47:1920.
3. Irvine, AA, Cox, D. Gonder-Frederick, L. Fear of hypoglycemia: Relationship to physical symptoms in patients with insulin-dependent diabetes. Health Psych 1992; 11:135.
4. Weinger, K, Kinsley, BT, Levy, CJ, et al. The perception of safe driving ability during hypoglycemia in patients with type 1 diabetes mellitus. Am J Med 1999; 107:246.
Diabetes type 1: Insulin treatment
INTRODUCTION — Diabetes mellitus is a lifelong condition that can be controlled with lifestyle adjustments and medical treatments. Keeping blood glucose levels under control can prevent or minimize complications. Insulin treatment is one component of a diabetes treatment plan that is necessary for all persons with type 1 diabetes.
Insulin treatment replaces or supplements the body's own insulin, restoring normal or near-normal blood glucose control. Many different types of insulin treatment can successfully control blood glucose levels; the best option depends upon a variety of individual factors. With a little extra planning, people with diabetes who take insulin can lead a full life and keep their blood glucose under control. (See "Patient information: Diabetes mellitus, type 2" and see "Patient information: Diabetes mellitus, type 1").
GOALS OF INSULIN TREATMENT — The goal of insulin treatment is to keep blood glucose levels at normal or near-normal levels. Careful control of blood glucose levels can help prevent both the short-term effects of poorly controlled blood glucose (such as diabetic ketoacidosis) and the long-term effects of poorly controlled blood glucose (diabetic complications of the eye, kidney, and cardiovascular system).
STARTING INSULIN — The pancreas produces very little or no insulin at all in people with type 1 diabetes. Some people have a "honeymoon" period soon after their diagnosis when insulin is not needed. Although it is tempting to stop insulin during this period, continuing insulin may preserve the person's ability to produce insulin for many months or years, making diabetes easier to control. All patients with type 1 diabetes will eventually require insulin.
Regimens — There are two general types of insulin treatment plans: standard (conventional) insulin treatment and intensive insulin treatment. They differ with regard to the type(s) and dose of insulin and the number of injections per day. In general, intensive insulin therapy is recommended for patients with type 1 diabetes (see "Intensive insulin treatment" below). Standard insulin treatment is an older regimen, although it may still be recommended for selected patients.
Dosing — When insulin treatment is started, small doses are generally recommended; the dose is adjusted over days, weeks, and months, once the body's response to insulin treatment is known. During this time, the patient must monitor the blood glucose level several times per day to determine the optimal dose of insulin.
Insulin needs often change over a person's lifetime. Changes in weight, diet, health conditions (including pregnancy), activity level, and occupation can affect the amount of insulin needed to control blood glucose levels. Patients are often able to adjust their own insulin dose, but most people require assistance in some situations. Most patients with type 1 diabetes meet with their healthcare provider every three to four months; blood glucose levels and insulin doses are reviewed at these visits, helping patients to fine-tune their diabetes control. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
Types — There are several different types of insulin. These types are classified according to how quickly they begin working and how long the insulin remains active (show table 1): Rapid-acting (eg, insulin lispro [Humalog®], insulin aspart [Novolog®], and insulin glulisine [Apidra®]) Short-acting (eg, insulin regular) Intermediate-acting (eg, insulin NPH) Long-acting (eg, insulin glargine [Lantus®], insulin detemir [Levemir®])
Insulin types can be used in combination to achieve around-the-clock blood glucose control.
INSULIN ADMINISTRATION — Insulin is ineffective when taken orally, and must therefore be given by other routes. Insulin is usually injected into the layer of fat under the skin (called subcutaneous injection). The following figure demonstrates the sites where insulin may be injected (show figure 1).
Patients as well as parents or partners should learn to draw up and inject insulin. An inhaled form of insulin is also available, although its role has not yet been fully defined (see "Inhaled insulin" below).
Needle and syringe — A needle and syringe are usually used to draw up and inject insulin under the skin. The needle must be injected at the correct angle since injecting too deeply could deliver insulin to the muscle, where it is absorbed quickly. Injecting too shallowly deposits insulin in the skin, which is painful and prevents the body from absorbing the insulin.
The best angle for insulin injection depends upon a patient's body type, injection site, and length of the needle used. A healthcare professional can help determine the right angle of injection.
Drawing up insulin — There are many different types of syringes and needles, so it's best to get specific instructions from a healthcare provider. Basic information is provided in the table. Persons using an insulin pen should follow the instructions for dosing and administration provided by the pen manufacturer and their clinician (see "Insulin pen injectors" below).
Before drawing up insulin, it is important to know the dose and type of insulin needed. If more than one type of insulin are combined in one syringe, the person drawing up the insulin should calculate the total dose before drawing up their insulin. Some persons, including children and those with difficulty seeing, may need assistance. Devices to magnify the syringe marking and simplify the drawing up process are available.
Injection technique — The following is a description of subcutaneous insulin injection. Choose the site to inject (show figure 1). It is not necessary to clean the skin with alcohol unless the skin is dirty. Pinch up a fold of skin and quickly insert the needle at a 90ยบ angle (or other angle, as described above, show figure 2). Keep the skin pinched to avoid injecting insulin into the muscle. Push the plunger down completely to inject the insulin. Hold the syringe and needle in place for 5 seconds. Release the skin fold. Remove the needle from the skin.
If blood or clear fluid (insulin) is seen at the injection site, the patient should apply pressure to the area for 5 to 8 seconds, but the area should not be rubbed.
Needles and syringes should only be used once and then thrown away. Used needles and syringes should not be included with regular household trash, but should instead be placed in a puncture-proof container (also known as a sharps container), available from most pharmacies or hospital supply stores.
Some patients wonder about the safety of injecting insulin through their clothing. One small study examined the risks and benefits of this technique, and found that blood glucose control did not differ between the group that injected insulin through a single layer of clothing and those that injected directly into the skin [1]. There were no reports of infections in either group, although a few patients who injected through clothing reported blood stains on their clothing or bruises on the skin. People who are interested in using this technique should speak with their healthcare provider before trying it.
Insulin pen injectors — Insulin pen injectors may be more convenient to carry and use when away from home. Most are approximately the size of a large writing pen, and contain a disposable insulin cartridge and needle. Some types of insulin and some insulin mixtures are not available in cartridges, meaning pens may not be used by all persons.
Pens are especially useful for accurately injecting very small doses of insulin, and may be helpful for persons with impaired vision. Pens are generally more expensive than traditional syringes and needles. A number of insulin pens are available, and the specific instructions for use of each type should be obtained from the manufacturer or a healthcare provider.
Inhaled insulin — An inhaled form of rapid-acting insulin is available; it is usually combined with long-acting insulin that is injected. When insulin is inhaled, the onset of action is rapid; slightly faster than a subcutaneous injection of rapid acting insulin (like lispro, aspart or glulisine). However, the duration of action is longer.
A problem with inhaled insulin is that about 90 percent of the dose is lost in the mouth and upper airways. As a result, several companies are developing devices to improve delivery to the lungs, where it can be better absorbed.
The 1 mg blister of insulin (Exubera®) delivers the equivalent of about 2.7 units of insulin while the 3 mg blister delivers the equivalent of about 8 units of insulin. Thus, it is not suitable if small adjustments in dose are needed.
Inhaled insulin is not suitable for patients who have asthma. It can reduce lung function and causes cough in about 20 percent of people; periodic lung testing is recommended. None of these side effects are considered to be major problems.
There are no guidelines in the United States regarding the use of inhaled insulin. It is significantly more expensive that injected insulin, and in clinical studies, it does not improve blood glucose control compared to injected insulin.
Insulin pump — Insulin can be continuously administered by insulin pump, a process called continuous subcutaneous insulin infusion. An insulin pump may be recommended for patients who are willing to closely monitor their blood glucose levels, food intake, and other factors.
The pump is worn externally and is attached to the body with long, thin, flexible plastic tubing that has a needle or soft cannula (thin plastic tube), which is inserted and then left in place beneath the skin. The needle or cannula and tubing are changed every 48 to 72 hours by the patient. The pump stores rapid acting insulin in a cartridge. The pump is programmed to give a small dose of insulin continuously through the day and night. At meal times, the patient must program the pump to give an additional dose of insulin, based upon the amount of food to be eaten. The pump can be taken off for up to one hour without impacting blood glucose control; if it is taken off for longer periods of time, insulin injections are needed to maintain blood glucose control.
The insulin pump has advantages and disadvantages; it may be helpful to talk with a person who uses a pump before deciding to purchase it. Most pump manufacturers have a list of people willing to speak with prospective pump users. It may also be possible to use a trial pump for a few days before committing to it.
Advantages — Insulin pumps permit flexibility in the timing of meals and other day-to-day events, similar to intensive treatment regimens that combine very-rapid acting and long-acting insulins. This can be of great benefit for children or adults whose schedule varies from one day to the next. People who use an insulin pump do not require multiple daily injections; most patients who use the pump change their injection site every 48 to 72 hours.
The other major advantage of an insulin pump is that day-to-day variation in insulin absorption is greatly reduced compared to conventional injections of intermediate or long acting insulins. This can help reduce day-to-day variation in blood glucose levels.
Disadvantages — The cost of an insulin pump and supplies is greater than the cost of insulin syringes and needles, although most insurance carriers cover some portion of the expenses. Many patients who use a pump develop pump-associated problems, including infection at the injection site or pump malfunction; patients must take care to monitor blood glucose levels carefully since even a temporary disruption can lead to serious elevations in blood glucose. Some find the pump awkward, uncomfortable, or embarrassing; 30 percent of people who begin using a pump discontinue its use within five years.
FACTORS AFFECTING INSULIN ACTION — Several factors can affect how insulin is absorbed.
Volume of insulin injected — The dose of insulin injected affects the rate at which the body absorbs it. Larger doses of insulin may be absorbed more slowly than a small dose. With larger doses of insulin, the insulin may peak later or last longer than with small doses. This could mean that the patient's blood glucose level is higher than expected within a few hours after eating, but then becomes
Injection technique — The angle and depth of an insulin injection are important, as mentioned above (see "Needle and syringe" above).
Site of injection — Clinicians usually recommend rotating injection sites to minimize tissue irritation. However, it is important to keep in mind that insulin is absorbed at different rates in different areas of the body. Insulin is absorbed fastest from the abdominal area, slowest from the leg and buttock, and at an intermediate rate from the arm. This may vary with the amount of subcutaneous fat present; the greater the amount of subcutaneous fat, the more slowly insulin is absorbed (show figure 1).
Because of anatomic variations in absorption, it is reasonable to use the same general area for injections given at the same time of the day. Pre-meal insulin injections are absorbed fastest from the abdominal area, allowing for optimal coverage of carbohydrates consumed in a meal. Injection into the thigh or buttock may be best for the evening dose because the insulin will be absorbed more slowly during the night.
Subcutaneous blood flow — Any factors that alter the rate of blood flow to the subcutaneous tissue will alter insulin absorption. Smoking actually decreases blood flow to the subcutaneous tissue and decreases absorption of injected insulin. In contrast, factors that increase the skin temperature (such as exercise, saunas, hot baths, and massage of the injection site) will increase insulin absorption.
Time since opening the bottle — While most insulin remains potent and effective for up to a month after the bottle has been opened (if kept in the refrigerator between injections) the potency for intermediate or long acting insulin begins to decrease after 30 days. This can be a problem for people who require very small doses of insulin and for whom a bottle might last two months or more. It is advisable to start a new bottle at least every 30 days.
For rapid acting insulin used in pen injectors, it is acceptable to keep the pen injector unrefrigerated (in a bag or jacket pocket) for up to 14 days, provided that the pen is not exposed to temperature extremes. However, after 14 days, a new insulin cartridge or pen should be used, even if there is insulin left in the old cartridge.
Individual factors — The same dose of the same type of insulin may have different effects in different people with diabetes. Some trial and error is usually necessary to find the ideal type(s) and dose of insulin and schedule for each person.
SPECIAL SITUATIONS — Several special situations can complicate insulin treatment for a person with diabetes. With advance planning and careful calculation, these situations are less likely to cause serious difficulties. A healthcare provider can assist patients in handling these situations.
Eating out — Eating out can be challenging since ingredients used, calorie and fat content, and portion sizes are usually different from meals prepared at home. Patients can estimate the carbohydrate content of meals to calculate insulin dosage; nutrition information is often available from restaurants or a hand-held reference book. Hypo- and hyperglycemia can occur more easily in situations where new or different foods are eaten; thus patients should keep a fast-acting source of carbohydrates and blood glucose monitor on hand at all times.
Surgery — Patients who undergo surgery may be instructed not to eat for 8 to 12 hours before their procedure. A healthcare provider can help to determine the dose and timing of insulin before and after the procedure, especially if a patient will be unable to eat a normal diet afterwards.
Infections — Mild infections, such as a cold, sore throat, or urinary tract infection, can cause blood glucose levels to rise and can even lead to diabetic ketoacidosis. In this situation, frequent telephone contact with a healthcare provider, careful blood glucose monitoring, and increasing the insulin dose are often recommended. Patients with nausea or vomiting may require medication to control their symptoms and avoid dehydration and ketoacidosis. If dehydration occurs, intravenous fluid replacement may be necessary.
Travel — Managing blood glucose levels and insulin treatment while traveling can be difficult, especially when traveling across multiple time zones. In addition, activity levels and diet are often different while traveling, making careful blood glucose monitoring essential. Patients should speak with their healthcare provider before traveling to develop a treatment plan. (See "Patient information: General travel advice" section on "Traveling with medical conditions").
INTENSIVE INSULIN TREATMENT — Intensive insulin treatment refers to treatment that tightly controls blood glucose levels; this treatment can achieve better control than standard insulin therapy regimens. Intensive insulin treatment requires multiple subcutaneous insulin injections or the use of an insulin pump in addition to frequent monitoring of blood glucose levels.
Most people with type 1 diabetes are candidates for intensive treatment; patients may begin when they are diagnosed or at a later time. Because it requires a serious commitment of time and effort, patients and families should learn as much as possible about intensive treatment before committing to it.
Benefits — Intensive insulin treatment can improve control of blood glucose, which can improve how a patient feels on a daily basis as well as reduce their risk of health complications later in life. A landmark study, the Diabetes Control and Complications Trial (DCCT) conclusively proved that the improved blood sugar control that results from intensive therapy means fewer long-term complications of diabetes.
Drawbacks — There are a few drawbacks to intensive insulin treatment: It requires careful management of daily activities, dietary intake, frequent insulin administration, exercise, and blood glucose monitoring (performed four to seven times per day). There is a three-fold increased risk of hypoglycemic episodes. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes"). Some patients gain weight (an average of about 10 pounds) initially, although exercise can counteract this effect. It is about three times as expensive as standard insulin treatment.
Staying motivated — Intensive treatment can be very demanding and some patients lose motivation over time. Healthcare providers can provide tips and encouragement to help patients stay on track. Helpful information and support is also available from the American Diabetes Association (ADA), at (800)-DIABETES (800-342-2383) and at www.diabetes.org.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov/)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
Canadian Diabetes Associates
(www.diabetes.ca)
Juvenile Diabetes Research Foundation
(www.jdrf.org)
U.S. Center for Disease Control and Prevention
(www.cdc.gov/diabetes)
[2-5]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Fleming, DR, Jacober, SJ, Vandenberg, MA, et al. The safety of injecting insulin through clothing. Diabetes Care 1997; 20:244.
2. Holman, RR, Turner, RC. A practical guide to basal and prandial insulin therapy. Diabet Med 1985; 2:45.
3. Yki-Jarvinen, H, Kauppila, M, Kujansuu, E, et al. Comparison of insulin regimens in patients with non-insulin-dependent diabetes mellitus. N Engl J Med 1992; 327:1426.
4. Koivisto, VA, Felig, P. Alterations in insulin absorption and in blood glucose control associated with varying insulin injection sites in diabetic patients. Ann Intern Med 1980; 92:59.
5. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
Insulin treatment replaces or supplements the body's own insulin, restoring normal or near-normal blood glucose control. Many different types of insulin treatment can successfully control blood glucose levels; the best option depends upon a variety of individual factors. With a little extra planning, people with diabetes who take insulin can lead a full life and keep their blood glucose under control. (See "Patient information: Diabetes mellitus, type 2" and see "Patient information: Diabetes mellitus, type 1").
GOALS OF INSULIN TREATMENT — The goal of insulin treatment is to keep blood glucose levels at normal or near-normal levels. Careful control of blood glucose levels can help prevent both the short-term effects of poorly controlled blood glucose (such as diabetic ketoacidosis) and the long-term effects of poorly controlled blood glucose (diabetic complications of the eye, kidney, and cardiovascular system).
STARTING INSULIN — The pancreas produces very little or no insulin at all in people with type 1 diabetes. Some people have a "honeymoon" period soon after their diagnosis when insulin is not needed. Although it is tempting to stop insulin during this period, continuing insulin may preserve the person's ability to produce insulin for many months or years, making diabetes easier to control. All patients with type 1 diabetes will eventually require insulin.
Regimens — There are two general types of insulin treatment plans: standard (conventional) insulin treatment and intensive insulin treatment. They differ with regard to the type(s) and dose of insulin and the number of injections per day. In general, intensive insulin therapy is recommended for patients with type 1 diabetes (see "Intensive insulin treatment" below). Standard insulin treatment is an older regimen, although it may still be recommended for selected patients.
Dosing — When insulin treatment is started, small doses are generally recommended; the dose is adjusted over days, weeks, and months, once the body's response to insulin treatment is known. During this time, the patient must monitor the blood glucose level several times per day to determine the optimal dose of insulin.
Insulin needs often change over a person's lifetime. Changes in weight, diet, health conditions (including pregnancy), activity level, and occupation can affect the amount of insulin needed to control blood glucose levels. Patients are often able to adjust their own insulin dose, but most people require assistance in some situations. Most patients with type 1 diabetes meet with their healthcare provider every three to four months; blood glucose levels and insulin doses are reviewed at these visits, helping patients to fine-tune their diabetes control. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
Types — There are several different types of insulin. These types are classified according to how quickly they begin working and how long the insulin remains active (show table 1): Rapid-acting (eg, insulin lispro [Humalog®], insulin aspart [Novolog®], and insulin glulisine [Apidra®]) Short-acting (eg, insulin regular) Intermediate-acting (eg, insulin NPH) Long-acting (eg, insulin glargine [Lantus®], insulin detemir [Levemir®])
Insulin types can be used in combination to achieve around-the-clock blood glucose control.
INSULIN ADMINISTRATION — Insulin is ineffective when taken orally, and must therefore be given by other routes. Insulin is usually injected into the layer of fat under the skin (called subcutaneous injection). The following figure demonstrates the sites where insulin may be injected (show figure 1).
Patients as well as parents or partners should learn to draw up and inject insulin. An inhaled form of insulin is also available, although its role has not yet been fully defined (see "Inhaled insulin" below).
Needle and syringe — A needle and syringe are usually used to draw up and inject insulin under the skin. The needle must be injected at the correct angle since injecting too deeply could deliver insulin to the muscle, where it is absorbed quickly. Injecting too shallowly deposits insulin in the skin, which is painful and prevents the body from absorbing the insulin.
The best angle for insulin injection depends upon a patient's body type, injection site, and length of the needle used. A healthcare professional can help determine the right angle of injection.
Drawing up insulin — There are many different types of syringes and needles, so it's best to get specific instructions from a healthcare provider. Basic information is provided in the table. Persons using an insulin pen should follow the instructions for dosing and administration provided by the pen manufacturer and their clinician (see "Insulin pen injectors" below).
Before drawing up insulin, it is important to know the dose and type of insulin needed. If more than one type of insulin are combined in one syringe, the person drawing up the insulin should calculate the total dose before drawing up their insulin. Some persons, including children and those with difficulty seeing, may need assistance. Devices to magnify the syringe marking and simplify the drawing up process are available.
Injection technique — The following is a description of subcutaneous insulin injection. Choose the site to inject (show figure 1). It is not necessary to clean the skin with alcohol unless the skin is dirty. Pinch up a fold of skin and quickly insert the needle at a 90ยบ angle (or other angle, as described above, show figure 2). Keep the skin pinched to avoid injecting insulin into the muscle. Push the plunger down completely to inject the insulin. Hold the syringe and needle in place for 5 seconds. Release the skin fold. Remove the needle from the skin.
If blood or clear fluid (insulin) is seen at the injection site, the patient should apply pressure to the area for 5 to 8 seconds, but the area should not be rubbed.
Needles and syringes should only be used once and then thrown away. Used needles and syringes should not be included with regular household trash, but should instead be placed in a puncture-proof container (also known as a sharps container), available from most pharmacies or hospital supply stores.
Some patients wonder about the safety of injecting insulin through their clothing. One small study examined the risks and benefits of this technique, and found that blood glucose control did not differ between the group that injected insulin through a single layer of clothing and those that injected directly into the skin [1]. There were no reports of infections in either group, although a few patients who injected through clothing reported blood stains on their clothing or bruises on the skin. People who are interested in using this technique should speak with their healthcare provider before trying it.
Insulin pen injectors — Insulin pen injectors may be more convenient to carry and use when away from home. Most are approximately the size of a large writing pen, and contain a disposable insulin cartridge and needle. Some types of insulin and some insulin mixtures are not available in cartridges, meaning pens may not be used by all persons.
Pens are especially useful for accurately injecting very small doses of insulin, and may be helpful for persons with impaired vision. Pens are generally more expensive than traditional syringes and needles. A number of insulin pens are available, and the specific instructions for use of each type should be obtained from the manufacturer or a healthcare provider.
Inhaled insulin — An inhaled form of rapid-acting insulin is available; it is usually combined with long-acting insulin that is injected. When insulin is inhaled, the onset of action is rapid; slightly faster than a subcutaneous injection of rapid acting insulin (like lispro, aspart or glulisine). However, the duration of action is longer.
A problem with inhaled insulin is that about 90 percent of the dose is lost in the mouth and upper airways. As a result, several companies are developing devices to improve delivery to the lungs, where it can be better absorbed.
The 1 mg blister of insulin (Exubera®) delivers the equivalent of about 2.7 units of insulin while the 3 mg blister delivers the equivalent of about 8 units of insulin. Thus, it is not suitable if small adjustments in dose are needed.
Inhaled insulin is not suitable for patients who have asthma. It can reduce lung function and causes cough in about 20 percent of people; periodic lung testing is recommended. None of these side effects are considered to be major problems.
There are no guidelines in the United States regarding the use of inhaled insulin. It is significantly more expensive that injected insulin, and in clinical studies, it does not improve blood glucose control compared to injected insulin.
Insulin pump — Insulin can be continuously administered by insulin pump, a process called continuous subcutaneous insulin infusion. An insulin pump may be recommended for patients who are willing to closely monitor their blood glucose levels, food intake, and other factors.
The pump is worn externally and is attached to the body with long, thin, flexible plastic tubing that has a needle or soft cannula (thin plastic tube), which is inserted and then left in place beneath the skin. The needle or cannula and tubing are changed every 48 to 72 hours by the patient. The pump stores rapid acting insulin in a cartridge. The pump is programmed to give a small dose of insulin continuously through the day and night. At meal times, the patient must program the pump to give an additional dose of insulin, based upon the amount of food to be eaten. The pump can be taken off for up to one hour without impacting blood glucose control; if it is taken off for longer periods of time, insulin injections are needed to maintain blood glucose control.
The insulin pump has advantages and disadvantages; it may be helpful to talk with a person who uses a pump before deciding to purchase it. Most pump manufacturers have a list of people willing to speak with prospective pump users. It may also be possible to use a trial pump for a few days before committing to it.
Advantages — Insulin pumps permit flexibility in the timing of meals and other day-to-day events, similar to intensive treatment regimens that combine very-rapid acting and long-acting insulins. This can be of great benefit for children or adults whose schedule varies from one day to the next. People who use an insulin pump do not require multiple daily injections; most patients who use the pump change their injection site every 48 to 72 hours.
The other major advantage of an insulin pump is that day-to-day variation in insulin absorption is greatly reduced compared to conventional injections of intermediate or long acting insulins. This can help reduce day-to-day variation in blood glucose levels.
Disadvantages — The cost of an insulin pump and supplies is greater than the cost of insulin syringes and needles, although most insurance carriers cover some portion of the expenses. Many patients who use a pump develop pump-associated problems, including infection at the injection site or pump malfunction; patients must take care to monitor blood glucose levels carefully since even a temporary disruption can lead to serious elevations in blood glucose. Some find the pump awkward, uncomfortable, or embarrassing; 30 percent of people who begin using a pump discontinue its use within five years.
FACTORS AFFECTING INSULIN ACTION — Several factors can affect how insulin is absorbed.
Volume of insulin injected — The dose of insulin injected affects the rate at which the body absorbs it. Larger doses of insulin may be absorbed more slowly than a small dose. With larger doses of insulin, the insulin may peak later or last longer than with small doses. This could mean that the patient's blood glucose level is higher than expected within a few hours after eating, but then becomes
Injection technique — The angle and depth of an insulin injection are important, as mentioned above (see "Needle and syringe" above).
Site of injection — Clinicians usually recommend rotating injection sites to minimize tissue irritation. However, it is important to keep in mind that insulin is absorbed at different rates in different areas of the body. Insulin is absorbed fastest from the abdominal area, slowest from the leg and buttock, and at an intermediate rate from the arm. This may vary with the amount of subcutaneous fat present; the greater the amount of subcutaneous fat, the more slowly insulin is absorbed (show figure 1).
Because of anatomic variations in absorption, it is reasonable to use the same general area for injections given at the same time of the day. Pre-meal insulin injections are absorbed fastest from the abdominal area, allowing for optimal coverage of carbohydrates consumed in a meal. Injection into the thigh or buttock may be best for the evening dose because the insulin will be absorbed more slowly during the night.
Subcutaneous blood flow — Any factors that alter the rate of blood flow to the subcutaneous tissue will alter insulin absorption. Smoking actually decreases blood flow to the subcutaneous tissue and decreases absorption of injected insulin. In contrast, factors that increase the skin temperature (such as exercise, saunas, hot baths, and massage of the injection site) will increase insulin absorption.
Time since opening the bottle — While most insulin remains potent and effective for up to a month after the bottle has been opened (if kept in the refrigerator between injections) the potency for intermediate or long acting insulin begins to decrease after 30 days. This can be a problem for people who require very small doses of insulin and for whom a bottle might last two months or more. It is advisable to start a new bottle at least every 30 days.
For rapid acting insulin used in pen injectors, it is acceptable to keep the pen injector unrefrigerated (in a bag or jacket pocket) for up to 14 days, provided that the pen is not exposed to temperature extremes. However, after 14 days, a new insulin cartridge or pen should be used, even if there is insulin left in the old cartridge.
Individual factors — The same dose of the same type of insulin may have different effects in different people with diabetes. Some trial and error is usually necessary to find the ideal type(s) and dose of insulin and schedule for each person.
SPECIAL SITUATIONS — Several special situations can complicate insulin treatment for a person with diabetes. With advance planning and careful calculation, these situations are less likely to cause serious difficulties. A healthcare provider can assist patients in handling these situations.
Eating out — Eating out can be challenging since ingredients used, calorie and fat content, and portion sizes are usually different from meals prepared at home. Patients can estimate the carbohydrate content of meals to calculate insulin dosage; nutrition information is often available from restaurants or a hand-held reference book. Hypo- and hyperglycemia can occur more easily in situations where new or different foods are eaten; thus patients should keep a fast-acting source of carbohydrates and blood glucose monitor on hand at all times.
Surgery — Patients who undergo surgery may be instructed not to eat for 8 to 12 hours before their procedure. A healthcare provider can help to determine the dose and timing of insulin before and after the procedure, especially if a patient will be unable to eat a normal diet afterwards.
Infections — Mild infections, such as a cold, sore throat, or urinary tract infection, can cause blood glucose levels to rise and can even lead to diabetic ketoacidosis. In this situation, frequent telephone contact with a healthcare provider, careful blood glucose monitoring, and increasing the insulin dose are often recommended. Patients with nausea or vomiting may require medication to control their symptoms and avoid dehydration and ketoacidosis. If dehydration occurs, intravenous fluid replacement may be necessary.
Travel — Managing blood glucose levels and insulin treatment while traveling can be difficult, especially when traveling across multiple time zones. In addition, activity levels and diet are often different while traveling, making careful blood glucose monitoring essential. Patients should speak with their healthcare provider before traveling to develop a treatment plan. (See "Patient information: General travel advice" section on "Traveling with medical conditions").
INTENSIVE INSULIN TREATMENT — Intensive insulin treatment refers to treatment that tightly controls blood glucose levels; this treatment can achieve better control than standard insulin therapy regimens. Intensive insulin treatment requires multiple subcutaneous insulin injections or the use of an insulin pump in addition to frequent monitoring of blood glucose levels.
Most people with type 1 diabetes are candidates for intensive treatment; patients may begin when they are diagnosed or at a later time. Because it requires a serious commitment of time and effort, patients and families should learn as much as possible about intensive treatment before committing to it.
Benefits — Intensive insulin treatment can improve control of blood glucose, which can improve how a patient feels on a daily basis as well as reduce their risk of health complications later in life. A landmark study, the Diabetes Control and Complications Trial (DCCT) conclusively proved that the improved blood sugar control that results from intensive therapy means fewer long-term complications of diabetes.
Drawbacks — There are a few drawbacks to intensive insulin treatment: It requires careful management of daily activities, dietary intake, frequent insulin administration, exercise, and blood glucose monitoring (performed four to seven times per day). There is a three-fold increased risk of hypoglycemic episodes. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes"). Some patients gain weight (an average of about 10 pounds) initially, although exercise can counteract this effect. It is about three times as expensive as standard insulin treatment.
Staying motivated — Intensive treatment can be very demanding and some patients lose motivation over time. Healthcare providers can provide tips and encouragement to help patients stay on track. Helpful information and support is also available from the American Diabetes Association (ADA), at (800)-DIABETES (800-342-2383) and at www.diabetes.org.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov/)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
Canadian Diabetes Associates
(www.diabetes.ca)
Juvenile Diabetes Research Foundation
(www.jdrf.org)
U.S. Center for Disease Control and Prevention
(www.cdc.gov/diabetes)
[2-5]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Fleming, DR, Jacober, SJ, Vandenberg, MA, et al. The safety of injecting insulin through clothing. Diabetes Care 1997; 20:244.
2. Holman, RR, Turner, RC. A practical guide to basal and prandial insulin therapy. Diabet Med 1985; 2:45.
3. Yki-Jarvinen, H, Kauppila, M, Kujansuu, E, et al. Comparison of insulin regimens in patients with non-insulin-dependent diabetes mellitus. N Engl J Med 1992; 327:1426.
4. Koivisto, VA, Felig, P. Alterations in insulin absorption and in blood glucose control associated with varying insulin injection sites in diabetic patients. Ann Intern Med 1980; 92:59.
5. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
Diabetes mellitus, type 1
INTRODUCTION — Type 1 diabetes mellitus is a chronic medical condition that occurs when the pancreas, an organ in the abdomen, produces very little or no insulin (show figure 1). Insulin is a hormone that helps the body to absorb and use glucose and other nutrients from food, store fat, and build up protein. Without insulin, blood glucose (sugar) levels become elevated.
Elevated blood glucose levels (called hyperglycemia) cause a person to urinate more frequently, causing loss of body water and dehydration. A person can also feel tired and lose weight. In addition, a serious and potentially life-threatening complication known as diabetic ketoacidosis can develop (see "Symptoms" below). Long term complications associated with hyperglycemia can affect the eyes, nerves, kidneys, and cardiovascular system, leading to blindness, loss of sensation in the feet, the need for amputation of toes or a foot, kidney failure, and an increased risk of heart attack and stroke.
Type 1 diabetes requires regular blood glucose monitoring and treatment with insulin. Treatment, lifestyle adjustments, and self-care can effectively control blood glucose levels and minimize a person's risk of ketoacidosis and other disease-related complications.
Type 1 diabetes usually begins in childhood or young adulthood, but can develop at any age. In the United States, Canada, and Europe, type 1 diabetes accounts for 5 to 10 percent of all cases of diabetes. It is relatively more common in people who are white compared to people of African or Asian descent.
THE IMPACT OF DIABETES — Being diagnosed with type 1 diabetes can be a frightening and overwhelming experience for some patients, and it is common to have questions about why it developed, what it means for long-term health, and how it will affect everyday life. For most patients, the first few months after being diagnosed are filled with emotional highs and lows. Persons with newly-diagnosed diabetes, as well as their families, can use this time to learn as much as possible so that diabetes-related care (eg, self-blood glucose testing, medical appointments, daily insulin) becomes a "normal" part of the daily routine. (See "Patient information: Self-blood glucose monitoring").
In addition, persons who are newly diagnosed should talk to their healthcare provider about resources that are available for medical as well as psychological support. This may include group classes, meetings with a nutritionist, social worker, or nurse educator, and other educational resources such as books, web sites, or magazines. Several of these resources are listed in this topic review (see "Where to get more information" below).
Despite the risks associated with type 1 diabetes, most persons can lead active lives and continue to enjoy the foods and activities that they previously enjoyed. Diabetes does not mean an end to special occasion foods like birthday cake, and with a little advanced planning, most persons with diabetes can enjoy exercise in almost any form.
CAUSES — Type 1 diabetes usually develops when a person's immune system destroys the insulin-producing cells (called the beta cells) in the pancreas. This is called an autoimmune response. This process occurs over many months or years, during which a person has no signs or symptoms of diabetes. Hyperglycemia and its associated symptoms (frequent urination, thirst) do not usually occur until more than 90 percent of the beta cells have been destroyed, which greatly reduces insulin secretion. The cause of the abnormal immune response that destroys the beta cells is being actively studied.
Type 1 diabetes may develop in persons with a family history of type 1 diabetes, but may also develop in persons with no family history of diabetes. In either case, the person has one or more genes that make them susceptible to the disease. Environmental factors, such as exposure to certain viruses and foods early in life, may trigger the autoimmune response.
DIAGNOSIS — The diagnosis of diabetes is based upon a person's symptoms and the results of laboratory tests.
Symptoms — Most people have symptoms of high blood glucose levels (hyperglycemia) before being diagnosed with type 1 diabetes. These symptoms may include excessive thirst, fatigue, frequent urination, weight loss, or blurred vision.
Less commonly, a person will develop signs and symptoms of diabetic ketoacidosis (DKA) at the time of diagnosis. DKA causes symptoms of high blood glucose levels (see above), as well as nausea and vomiting, abdominal pain, rapid breathing, lethargy, decreased alertness, and sometimes coma. DKA is a medical emergency and must be treated promptly.
Rarely, type 1 diabetes is diagnosed before symptoms develop.
Laboratory tests — Several blood tests are used to measure blood glucose levels; this is the primary test for diagnosing diabetes. Additional tests can determine the type of diabetes and its severity. Random blood glucose test — For a random blood glucose test, blood can be drawn at any time throughout the day, regardless of when the person last ate. A random blood glucose level of 200 mg/dL (11.1 mmol/L) or higher in a person who has the typical symptoms of hyperglycemia suggests a diagnosis of diabetes. Fasting blood glucose test — Fasting blood glucose testing involves measurement of blood glucose after not eating or drinking for 8 to 12 hours (usually overnight). Fasting blood glucose is normally less than 100 mg/dL (5.6 mmol/L); values of 126 mg/dL (7.0 mmol/L) or higher suggests diabetes. However, the test must be repeated on another day to confirm the diagnosis of diabetes. Hemoglobin A1C test (A1C) — The A1C blood test measures the average blood glucose level during the past two to three months. It is used to monitor blood glucose control in people with known diabetes, but is not used to diagnose the disease. Normal values for A1C are usually 6.1 percent or lower (indicating an average blood glucose of 120 mg/dL [6.6 mmol/L], show figure 2). Most healthcare providers recommend measuring A1C three to four times per year in people with type 1 diabetes.
Criteria for diagnosis — The following criteria are used to define blood glucose levels as normal or indicative of diabetes. Normal — Fasting plasma glucose (FPG) <100 mg/dL (5.6 mmol/L). Diabetes mellitus — A person is diagnosed with diabetes if he or she has one or more of the following criteria:
- Symptoms of diabetes (see "Symptoms" above) and a fasting blood glucose level of 126 mg/dL (7.0 mmol/L) or higher
- Symptoms and a random blood glucose of 200 mg/dL (11.1 mmol/L) or higher
The blood tests must be repeated on another day to confirm that they remain abnormally high.
Type 1 versus type 2 diabetes — A healthcare provider is usually able to determine whether a patient has type 1 or type 2 diabetes based upon the need for insulin (which is needed from the beginning in type 1, and less commonly early in type 2), and the presence of ketones in the urine when blood glucose levels are elevated (common in type 1, uncommon in type 2). Other factors, such as age at diagnosis (generally younger for type 1), obesity (more common in type 2), and the presence of antibodies in the blood (present in type 1) can be used to distinguish between the two types. (See "Patient information: Diabetes mellitus, type 2").
However, there are situations where it is not clear if a person has type 1 or 2 diabetes. In this situation, a healthcare provider usually treats the patient as if they have type 1, since missing this diagnosis can result in DKA.
RISK FACTORS — A person whose parent or sibling has type 1 diabetes is at increased risk of developing the disease, compared to a person with no family history (5 to 6 percent versus 0.4 percent, respectively). To determine if a person with a family history of type 1 diabetes is at increased risk, genetic testing can be performed. Currently these tests are only available to those who participate in a clinical research trial. Persons who are found to be at risk for developing type 1 diabetes may be enrolled in further clinical trials aimed at preventing or delaying the disease from developing.
PREVENTION — Methods to prevent type 1 diabetes are still in the investigational stage. Currently, no treatment has been found to be effective in preventing type 1 diabetes for more than a brief period of time.
TREATMENT — Treatment of diabetes requires a team approach, including the patient and their family and healthcare providers (physician, nurse, diabetes educator, dietitian), and sometimes other clinicians (exercise physiologist, podiatrist, etc). The treatment of type 1 diabetes is discussed on a separate topic review. (See "Patient information: Diabetes type 1: Insulin treatment").
LONG-TERM OUTCOMES — Several studies have proven that persons with diabetes whose blood glucose levels are kept at near-normal levels can reduce their risk of long-term complications. In the Diabetes Control and Complications Trial, 1441 patients were followed for 6.5 years. Half the group used intensive insulin therapy (either with an insulin pump or three or more insulin injections daily) with the goal of maintaining glucose levels as close to the non-diabetic range as possible. The other half used conventional therapy (one to two insulin injections per day). Intensive therapy reduced the risk of retinopathy by 76 percent, nephropathy by 54 percent, and neuropathy by 60 percent [1]. Longer-term study of the DCCT population has shown that heart disease and strokes are also reduced with intensive diabetes therapy.
Thus, persons with diabetes can greatly reduce their risk of long-term complications by monitoring blood glucose levels frequently and using intensive insulin therapy. The goal A1C is as close to the non-diabetic range as possible and, at a minimum, should be less than 7 percent.
The life expectancy for persons with diabetes is based upon many factors, including the development of diabetes-related complications, lifestyle factors such as smoking, diet, exercise, and alcohol consumption, weight and other medical conditions.
COMPLICATIONS — Complications of type 1 diabetes are related to the disease itself as well as to the treatments that are necessary to manage diabetes. (See "Patient information: Preventing complications in diabetes mellitus").
Disease-related complications — Persons with type 1 diabetes are at increased risk of cardiovascular disease, which can cause myocardial infarction (heart attack), angina (chest pain), stroke, and death. The risk is estimated to be at least twice that of nondiabetics. However, persons with type 1 diabetes can substantially lower their risk of cardiovascular disease by not smoking, taking a low-dose aspirin every day (for adults only), and by managing high blood pressure and hyperlipidemia with diet, exercise, and medications, and by achieving an A1C level of 7 percent or lower. (See "Patient information: High cholesterol and lipids (hyperlipidemia)" and see "Patient information: High blood pressure treatment" and see "Patient information: Smoking cessation" and see "Patient information: Aspirin and heart disease").
The more specific complications of type 1 diabetes include damage to small blood vessels (called microvascular damage) and nerves. This damage is the result of elevated blood glucose levels over a period of many years; improving blood glucose control can prevent or reduce the risk of these complications.
Microvascular damage affects the retina in the eyes (the light-sensitive film in the back of the eyes). This is called retinopathy, which can lead to decreased vision or blindness. Microvascular damage also affects the kidneys (called nephropathy, which can lead to kidney failure), and nerves (called neuropathy, which can cause pain and increases the risk of foot injury and infection). The risk of nephropathy, neuropathy, and retinopathy is related to the level of the A1C; the higher the A1C value, the greater the risk (show figure 3 and show figure 4). Other factors, especially high blood pressure, increase the risk of diabetic complications. (See "Patient information: Foot care in diabetes").
Treatment-related complications — Treatment-related complications of type 1 diabetes are more common in persons who use intensive insulin therapy. Intensive insulin therapy involves giving three or more insulin injections daily, or use of an insulin pump. Complications of this type of treatment can include hypoglycemia (low blood sugar) and weight gain. However, intensive insulin therapy has significant benefits despite these treatment-related risks. (See "Patient information: Diabetes type 1: Insulin treatment").
Results from a large trial demonstrated that the risk of hypoglycemia increased as the A1C was lowered. However, there is wide variability in the rate of hypoglycemia for a given A1C value. Thus, each patient must find his or her own level of tolerance. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
Weight gain is also a common problem with intensive insulin regimens. Weight gain can be prevented or managed with regular exercise and careful attention to diet.
PREGNANCY AND DIABETES — Women with type 1 diabetes are usually able to become pregnant and have a healthy baby. However, it is important to tightly control blood glucose levels before and during pregnancy to minimize the risk of complications. A full discussion of this topic is available separately. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-6]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
2. Alberti, KG, Zimmet, PZ for the WHO Consultation. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: Diagnosis and classification of diabetes mellitus. Provisional report of a WHO consultation. Diabet Med 1998; 15:539.
3. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 1997; 20:1183.
4. Nathan, DM, Cleary, PA, Backlund, JY, et al. Intensive diabetes treatment and cardiovascular disease in patients with type 1 diabetes. N Engl J Med 2005; 353:2643.
5. Retinopathy and nephropathy in patients with type 1 diabetes four years after a trial of intensive therapy. The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Research Group. N Engl J Med 2000; 342:381.
6. LaGasse, JM, Brantley, MS, Leech, NJ, et al. Successful prospective prediction of type 1 diabetes in schoolchildren through multiple defined autoantibodies: an 8-year follow-up of the Washington State Diabetes Prediction Study. Diabetes Care 2002; 25:505.
Elevated blood glucose levels (called hyperglycemia) cause a person to urinate more frequently, causing loss of body water and dehydration. A person can also feel tired and lose weight. In addition, a serious and potentially life-threatening complication known as diabetic ketoacidosis can develop (see "Symptoms" below). Long term complications associated with hyperglycemia can affect the eyes, nerves, kidneys, and cardiovascular system, leading to blindness, loss of sensation in the feet, the need for amputation of toes or a foot, kidney failure, and an increased risk of heart attack and stroke.
Type 1 diabetes requires regular blood glucose monitoring and treatment with insulin. Treatment, lifestyle adjustments, and self-care can effectively control blood glucose levels and minimize a person's risk of ketoacidosis and other disease-related complications.
Type 1 diabetes usually begins in childhood or young adulthood, but can develop at any age. In the United States, Canada, and Europe, type 1 diabetes accounts for 5 to 10 percent of all cases of diabetes. It is relatively more common in people who are white compared to people of African or Asian descent.
THE IMPACT OF DIABETES — Being diagnosed with type 1 diabetes can be a frightening and overwhelming experience for some patients, and it is common to have questions about why it developed, what it means for long-term health, and how it will affect everyday life. For most patients, the first few months after being diagnosed are filled with emotional highs and lows. Persons with newly-diagnosed diabetes, as well as their families, can use this time to learn as much as possible so that diabetes-related care (eg, self-blood glucose testing, medical appointments, daily insulin) becomes a "normal" part of the daily routine. (See "Patient information: Self-blood glucose monitoring").
In addition, persons who are newly diagnosed should talk to their healthcare provider about resources that are available for medical as well as psychological support. This may include group classes, meetings with a nutritionist, social worker, or nurse educator, and other educational resources such as books, web sites, or magazines. Several of these resources are listed in this topic review (see "Where to get more information" below).
Despite the risks associated with type 1 diabetes, most persons can lead active lives and continue to enjoy the foods and activities that they previously enjoyed. Diabetes does not mean an end to special occasion foods like birthday cake, and with a little advanced planning, most persons with diabetes can enjoy exercise in almost any form.
CAUSES — Type 1 diabetes usually develops when a person's immune system destroys the insulin-producing cells (called the beta cells) in the pancreas. This is called an autoimmune response. This process occurs over many months or years, during which a person has no signs or symptoms of diabetes. Hyperglycemia and its associated symptoms (frequent urination, thirst) do not usually occur until more than 90 percent of the beta cells have been destroyed, which greatly reduces insulin secretion. The cause of the abnormal immune response that destroys the beta cells is being actively studied.
Type 1 diabetes may develop in persons with a family history of type 1 diabetes, but may also develop in persons with no family history of diabetes. In either case, the person has one or more genes that make them susceptible to the disease. Environmental factors, such as exposure to certain viruses and foods early in life, may trigger the autoimmune response.
DIAGNOSIS — The diagnosis of diabetes is based upon a person's symptoms and the results of laboratory tests.
Symptoms — Most people have symptoms of high blood glucose levels (hyperglycemia) before being diagnosed with type 1 diabetes. These symptoms may include excessive thirst, fatigue, frequent urination, weight loss, or blurred vision.
Less commonly, a person will develop signs and symptoms of diabetic ketoacidosis (DKA) at the time of diagnosis. DKA causes symptoms of high blood glucose levels (see above), as well as nausea and vomiting, abdominal pain, rapid breathing, lethargy, decreased alertness, and sometimes coma. DKA is a medical emergency and must be treated promptly.
Rarely, type 1 diabetes is diagnosed before symptoms develop.
Laboratory tests — Several blood tests are used to measure blood glucose levels; this is the primary test for diagnosing diabetes. Additional tests can determine the type of diabetes and its severity. Random blood glucose test — For a random blood glucose test, blood can be drawn at any time throughout the day, regardless of when the person last ate. A random blood glucose level of 200 mg/dL (11.1 mmol/L) or higher in a person who has the typical symptoms of hyperglycemia suggests a diagnosis of diabetes. Fasting blood glucose test — Fasting blood glucose testing involves measurement of blood glucose after not eating or drinking for 8 to 12 hours (usually overnight). Fasting blood glucose is normally less than 100 mg/dL (5.6 mmol/L); values of 126 mg/dL (7.0 mmol/L) or higher suggests diabetes. However, the test must be repeated on another day to confirm the diagnosis of diabetes. Hemoglobin A1C test (A1C) — The A1C blood test measures the average blood glucose level during the past two to three months. It is used to monitor blood glucose control in people with known diabetes, but is not used to diagnose the disease. Normal values for A1C are usually 6.1 percent or lower (indicating an average blood glucose of 120 mg/dL [6.6 mmol/L], show figure 2). Most healthcare providers recommend measuring A1C three to four times per year in people with type 1 diabetes.
Criteria for diagnosis — The following criteria are used to define blood glucose levels as normal or indicative of diabetes. Normal — Fasting plasma glucose (FPG) <100 mg/dL (5.6 mmol/L). Diabetes mellitus — A person is diagnosed with diabetes if he or she has one or more of the following criteria:
- Symptoms of diabetes (see "Symptoms" above) and a fasting blood glucose level of 126 mg/dL (7.0 mmol/L) or higher
- Symptoms and a random blood glucose of 200 mg/dL (11.1 mmol/L) or higher
The blood tests must be repeated on another day to confirm that they remain abnormally high.
Type 1 versus type 2 diabetes — A healthcare provider is usually able to determine whether a patient has type 1 or type 2 diabetes based upon the need for insulin (which is needed from the beginning in type 1, and less commonly early in type 2), and the presence of ketones in the urine when blood glucose levels are elevated (common in type 1, uncommon in type 2). Other factors, such as age at diagnosis (generally younger for type 1), obesity (more common in type 2), and the presence of antibodies in the blood (present in type 1) can be used to distinguish between the two types. (See "Patient information: Diabetes mellitus, type 2").
However, there are situations where it is not clear if a person has type 1 or 2 diabetes. In this situation, a healthcare provider usually treats the patient as if they have type 1, since missing this diagnosis can result in DKA.
RISK FACTORS — A person whose parent or sibling has type 1 diabetes is at increased risk of developing the disease, compared to a person with no family history (5 to 6 percent versus 0.4 percent, respectively). To determine if a person with a family history of type 1 diabetes is at increased risk, genetic testing can be performed. Currently these tests are only available to those who participate in a clinical research trial. Persons who are found to be at risk for developing type 1 diabetes may be enrolled in further clinical trials aimed at preventing or delaying the disease from developing.
PREVENTION — Methods to prevent type 1 diabetes are still in the investigational stage. Currently, no treatment has been found to be effective in preventing type 1 diabetes for more than a brief period of time.
TREATMENT — Treatment of diabetes requires a team approach, including the patient and their family and healthcare providers (physician, nurse, diabetes educator, dietitian), and sometimes other clinicians (exercise physiologist, podiatrist, etc). The treatment of type 1 diabetes is discussed on a separate topic review. (See "Patient information: Diabetes type 1: Insulin treatment").
LONG-TERM OUTCOMES — Several studies have proven that persons with diabetes whose blood glucose levels are kept at near-normal levels can reduce their risk of long-term complications. In the Diabetes Control and Complications Trial, 1441 patients were followed for 6.5 years. Half the group used intensive insulin therapy (either with an insulin pump or three or more insulin injections daily) with the goal of maintaining glucose levels as close to the non-diabetic range as possible. The other half used conventional therapy (one to two insulin injections per day). Intensive therapy reduced the risk of retinopathy by 76 percent, nephropathy by 54 percent, and neuropathy by 60 percent [1]. Longer-term study of the DCCT population has shown that heart disease and strokes are also reduced with intensive diabetes therapy.
Thus, persons with diabetes can greatly reduce their risk of long-term complications by monitoring blood glucose levels frequently and using intensive insulin therapy. The goal A1C is as close to the non-diabetic range as possible and, at a minimum, should be less than 7 percent.
The life expectancy for persons with diabetes is based upon many factors, including the development of diabetes-related complications, lifestyle factors such as smoking, diet, exercise, and alcohol consumption, weight and other medical conditions.
COMPLICATIONS — Complications of type 1 diabetes are related to the disease itself as well as to the treatments that are necessary to manage diabetes. (See "Patient information: Preventing complications in diabetes mellitus").
Disease-related complications — Persons with type 1 diabetes are at increased risk of cardiovascular disease, which can cause myocardial infarction (heart attack), angina (chest pain), stroke, and death. The risk is estimated to be at least twice that of nondiabetics. However, persons with type 1 diabetes can substantially lower their risk of cardiovascular disease by not smoking, taking a low-dose aspirin every day (for adults only), and by managing high blood pressure and hyperlipidemia with diet, exercise, and medications, and by achieving an A1C level of 7 percent or lower. (See "Patient information: High cholesterol and lipids (hyperlipidemia)" and see "Patient information: High blood pressure treatment" and see "Patient information: Smoking cessation" and see "Patient information: Aspirin and heart disease").
The more specific complications of type 1 diabetes include damage to small blood vessels (called microvascular damage) and nerves. This damage is the result of elevated blood glucose levels over a period of many years; improving blood glucose control can prevent or reduce the risk of these complications.
Microvascular damage affects the retina in the eyes (the light-sensitive film in the back of the eyes). This is called retinopathy, which can lead to decreased vision or blindness. Microvascular damage also affects the kidneys (called nephropathy, which can lead to kidney failure), and nerves (called neuropathy, which can cause pain and increases the risk of foot injury and infection). The risk of nephropathy, neuropathy, and retinopathy is related to the level of the A1C; the higher the A1C value, the greater the risk (show figure 3 and show figure 4). Other factors, especially high blood pressure, increase the risk of diabetic complications. (See "Patient information: Foot care in diabetes").
Treatment-related complications — Treatment-related complications of type 1 diabetes are more common in persons who use intensive insulin therapy. Intensive insulin therapy involves giving three or more insulin injections daily, or use of an insulin pump. Complications of this type of treatment can include hypoglycemia (low blood sugar) and weight gain. However, intensive insulin therapy has significant benefits despite these treatment-related risks. (See "Patient information: Diabetes type 1: Insulin treatment").
Results from a large trial demonstrated that the risk of hypoglycemia increased as the A1C was lowered. However, there is wide variability in the rate of hypoglycemia for a given A1C value. Thus, each patient must find his or her own level of tolerance. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
Weight gain is also a common problem with intensive insulin regimens. Weight gain can be prevented or managed with regular exercise and careful attention to diet.
PREGNANCY AND DIABETES — Women with type 1 diabetes are usually able to become pregnant and have a healthy baby. However, it is important to tightly control blood glucose levels before and during pregnancy to minimize the risk of complications. A full discussion of this topic is available separately. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-6]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
2. Alberti, KG, Zimmet, PZ for the WHO Consultation. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: Diagnosis and classification of diabetes mellitus. Provisional report of a WHO consultation. Diabet Med 1998; 15:539.
3. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 1997; 20:1183.
4. Nathan, DM, Cleary, PA, Backlund, JY, et al. Intensive diabetes treatment and cardiovascular disease in patients with type 1 diabetes. N Engl J Med 2005; 353:2643.
5. Retinopathy and nephropathy in patients with type 1 diabetes four years after a trial of intensive therapy. The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Research Group. N Engl J Med 2000; 342:381.
6. LaGasse, JM, Brantley, MS, Leech, NJ, et al. Successful prospective prediction of type 1 diabetes in schoolchildren through multiple defined autoantibodies: an 8-year follow-up of the Washington State Diabetes Prediction Study. Diabetes Care 2002; 25:505.
Diabetes mellitus, type 1
INTRODUCTION — Type 1 diabetes mellitus is a chronic medical condition that occurs when the pancreas, an organ in the abdomen, produces very little or no insulin (show figure 1). Insulin is a hormone that helps the body to absorb and use glucose and other nutrients from food, store fat, and build up protein. Without insulin, blood glucose (sugar) levels become elevated.
Elevated blood glucose levels (called hyperglycemia) cause a person to urinate more frequently, causing loss of body water and dehydration. A person can also feel tired and lose weight. In addition, a serious and potentially life-threatening complication known as diabetic ketoacidosis can develop (see "Symptoms" below). Long term complications associated with hyperglycemia can affect the eyes, nerves, kidneys, and cardiovascular system, leading to blindness, loss of sensation in the feet, the need for amputation of toes or a foot, kidney failure, and an increased risk of heart attack and stroke.
Type 1 diabetes requires regular blood glucose monitoring and treatment with insulin. Treatment, lifestyle adjustments, and self-care can effectively control blood glucose levels and minimize a person's risk of ketoacidosis and other disease-related complications.
Type 1 diabetes usually begins in childhood or young adulthood, but can develop at any age. In the United States, Canada, and Europe, type 1 diabetes accounts for 5 to 10 percent of all cases of diabetes. It is relatively more common in people who are white compared to people of African or Asian descent.
THE IMPACT OF DIABETES — Being diagnosed with type 1 diabetes can be a frightening and overwhelming experience for some patients, and it is common to have questions about why it developed, what it means for long-term health, and how it will affect everyday life. For most patients, the first few months after being diagnosed are filled with emotional highs and lows. Persons with newly-diagnosed diabetes, as well as their families, can use this time to learn as much as possible so that diabetes-related care (eg, self-blood glucose testing, medical appointments, daily insulin) becomes a "normal" part of the daily routine. (See "Patient information: Self-blood glucose monitoring").
In addition, persons who are newly diagnosed should talk to their healthcare provider about resources that are available for medical as well as psychological support. This may include group classes, meetings with a nutritionist, social worker, or nurse educator, and other educational resources such as books, web sites, or magazines. Several of these resources are listed in this topic review (see "Where to get more information" below).
Despite the risks associated with type 1 diabetes, most persons can lead active lives and continue to enjoy the foods and activities that they previously enjoyed. Diabetes does not mean an end to special occasion foods like birthday cake, and with a little advanced planning, most persons with diabetes can enjoy exercise in almost any form.
CAUSES — Type 1 diabetes usually develops when a person's immune system destroys the insulin-producing cells (called the beta cells) in the pancreas. This is called an autoimmune response. This process occurs over many months or years, during which a person has no signs or symptoms of diabetes. Hyperglycemia and its associated symptoms (frequent urination, thirst) do not usually occur until more than 90 percent of the beta cells have been destroyed, which greatly reduces insulin secretion. The cause of the abnormal immune response that destroys the beta cells is being actively studied.
Type 1 diabetes may develop in persons with a family history of type 1 diabetes, but may also develop in persons with no family history of diabetes. In either case, the person has one or more genes that make them susceptible to the disease. Environmental factors, such as exposure to certain viruses and foods early in life, may trigger the autoimmune response.
DIAGNOSIS — The diagnosis of diabetes is based upon a person's symptoms and the results of laboratory tests.
Symptoms — Most people have symptoms of high blood glucose levels (hyperglycemia) before being diagnosed with type 1 diabetes. These symptoms may include excessive thirst, fatigue, frequent urination, weight loss, or blurred vision.
Less commonly, a person will develop signs and symptoms of diabetic ketoacidosis (DKA) at the time of diagnosis. DKA causes symptoms of high blood glucose levels (see above), as well as nausea and vomiting, abdominal pain, rapid breathing, lethargy, decreased alertness, and sometimes coma. DKA is a medical emergency and must be treated promptly.
Rarely, type 1 diabetes is diagnosed before symptoms develop.
Laboratory tests — Several blood tests are used to measure blood glucose levels; this is the primary test for diagnosing diabetes. Additional tests can determine the type of diabetes and its severity. Random blood glucose test — For a random blood glucose test, blood can be drawn at any time throughout the day, regardless of when the person last ate. A random blood glucose level of 200 mg/dL (11.1 mmol/L) or higher in a person who has the typical symptoms of hyperglycemia suggests a diagnosis of diabetes. Fasting blood glucose test — Fasting blood glucose testing involves measurement of blood glucose after not eating or drinking for 8 to 12 hours (usually overnight). Fasting blood glucose is normally less than 100 mg/dL (5.6 mmol/L); values of 126 mg/dL (7.0 mmol/L) or higher suggests diabetes. However, the test must be repeated on another day to confirm the diagnosis of diabetes. Hemoglobin A1C test (A1C) — The A1C blood test measures the average blood glucose level during the past two to three months. It is used to monitor blood glucose control in people with known diabetes, but is not used to diagnose the disease. Normal values for A1C are usually 6.1 percent or lower (indicating an average blood glucose of 120 mg/dL [6.6 mmol/L], show figure 2). Most healthcare providers recommend measuring A1C three to four times per year in people with type 1 diabetes.
Criteria for diagnosis — The following criteria are used to define blood glucose levels as normal or indicative of diabetes. Normal — Fasting plasma glucose (FPG) <100 mg/dL (5.6 mmol/L). Diabetes mellitus — A person is diagnosed with diabetes if he or she has one or more of the following criteria:
- Symptoms of diabetes (see "Symptoms" above) and a fasting blood glucose level of 126 mg/dL (7.0 mmol/L) or higher
- Symptoms and a random blood glucose of 200 mg/dL (11.1 mmol/L) or higher
The blood tests must be repeated on another day to confirm that they remain abnormally high.
Type 1 versus type 2 diabetes — A healthcare provider is usually able to determine whether a patient has type 1 or type 2 diabetes based upon the need for insulin (which is needed from the beginning in type 1, and less commonly early in type 2), and the presence of ketones in the urine when blood glucose levels are elevated (common in type 1, uncommon in type 2). Other factors, such as age at diagnosis (generally younger for type 1), obesity (more common in type 2), and the presence of antibodies in the blood (present in type 1) can be used to distinguish between the two types. (See "Patient information: Diabetes mellitus, type 2").
However, there are situations where it is not clear if a person has type 1 or 2 diabetes. In this situation, a healthcare provider usually treats the patient as if they have type 1, since missing this diagnosis can result in DKA.
RISK FACTORS — A person whose parent or sibling has type 1 diabetes is at increased risk of developing the disease, compared to a person with no family history (5 to 6 percent versus 0.4 percent, respectively). To determine if a person with a family history of type 1 diabetes is at increased risk, genetic testing can be performed. Currently these tests are only available to those who participate in a clinical research trial. Persons who are found to be at risk for developing type 1 diabetes may be enrolled in further clinical trials aimed at preventing or delaying the disease from developing.
PREVENTION — Methods to prevent type 1 diabetes are still in the investigational stage. Currently, no treatment has been found to be effective in preventing type 1 diabetes for more than a brief period of time.
TREATMENT — Treatment of diabetes requires a team approach, including the patient and their family and healthcare providers (physician, nurse, diabetes educator, dietitian), and sometimes other clinicians (exercise physiologist, podiatrist, etc). The treatment of type 1 diabetes is discussed on a separate topic review. (See "Patient information: Diabetes type 1: Insulin treatment").
LONG-TERM OUTCOMES — Several studies have proven that persons with diabetes whose blood glucose levels are kept at near-normal levels can reduce their risk of long-term complications. In the Diabetes Control and Complications Trial, 1441 patients were followed for 6.5 years. Half the group used intensive insulin therapy (either with an insulin pump or three or more insulin injections daily) with the goal of maintaining glucose levels as close to the non-diabetic range as possible. The other half used conventional therapy (one to two insulin injections per day). Intensive therapy reduced the risk of retinopathy by 76 percent, nephropathy by 54 percent, and neuropathy by 60 percent [1]. Longer-term study of the DCCT population has shown that heart disease and strokes are also reduced with intensive diabetes therapy.
Thus, persons with diabetes can greatly reduce their risk of long-term complications by monitoring blood glucose levels frequently and using intensive insulin therapy. The goal A1C is as close to the non-diabetic range as possible and, at a minimum, should be less than 7 percent.
The life expectancy for persons with diabetes is based upon many factors, including the development of diabetes-related complications, lifestyle factors such as smoking, diet, exercise, and alcohol consumption, weight and other medical conditions.
COMPLICATIONS — Complications of type 1 diabetes are related to the disease itself as well as to the treatments that are necessary to manage diabetes. (See "Patient information: Preventing complications in diabetes mellitus").
Disease-related complications — Persons with type 1 diabetes are at increased risk of cardiovascular disease, which can cause myocardial infarction (heart attack), angina (chest pain), stroke, and death. The risk is estimated to be at least twice that of nondiabetics. However, persons with type 1 diabetes can substantially lower their risk of cardiovascular disease by not smoking, taking a low-dose aspirin every day (for adults only), and by managing high blood pressure and hyperlipidemia with diet, exercise, and medications, and by achieving an A1C level of 7 percent or lower. (See "Patient information: High cholesterol and lipids (hyperlipidemia)" and see "Patient information: High blood pressure treatment" and see "Patient information: Smoking cessation" and see "Patient information: Aspirin and heart disease").
The more specific complications of type 1 diabetes include damage to small blood vessels (called microvascular damage) and nerves. This damage is the result of elevated blood glucose levels over a period of many years; improving blood glucose control can prevent or reduce the risk of these complications.
Microvascular damage affects the retina in the eyes (the light-sensitive film in the back of the eyes). This is called retinopathy, which can lead to decreased vision or blindness. Microvascular damage also affects the kidneys (called nephropathy, which can lead to kidney failure), and nerves (called neuropathy, which can cause pain and increases the risk of foot injury and infection). The risk of nephropathy, neuropathy, and retinopathy is related to the level of the A1C; the higher the A1C value, the greater the risk (show figure 3 and show figure 4). Other factors, especially high blood pressure, increase the risk of diabetic complications. (See "Patient information: Foot care in diabetes").
Treatment-related complications — Treatment-related complications of type 1 diabetes are more common in persons who use intensive insulin therapy. Intensive insulin therapy involves giving three or more insulin injections daily, or use of an insulin pump. Complications of this type of treatment can include hypoglycemia (low blood sugar) and weight gain. However, intensive insulin therapy has significant benefits despite these treatment-related risks. (See "Patient information: Diabetes type 1: Insulin treatment").
Results from a large trial demonstrated that the risk of hypoglycemia increased as the A1C was lowered. However, there is wide variability in the rate of hypoglycemia for a given A1C value. Thus, each patient must find his or her own level of tolerance. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
Weight gain is also a common problem with intensive insulin regimens. Weight gain can be prevented or managed with regular exercise and careful attention to diet.
PREGNANCY AND DIABETES — Women with type 1 diabetes are usually able to become pregnant and have a healthy baby. However, it is important to tightly control blood glucose levels before and during pregnancy to minimize the risk of complications. A full discussion of this topic is available separately. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-6]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
2. Alberti, KG, Zimmet, PZ for the WHO Consultation. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: Diagnosis and classification of diabetes mellitus. Provisional report of a WHO consultation. Diabet Med 1998; 15:539.
3. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 1997; 20:1183.
4. Nathan, DM, Cleary, PA, Backlund, JY, et al. Intensive diabetes treatment and cardiovascular disease in patients with type 1 diabetes. N Engl J Med 2005; 353:2643.
5. Retinopathy and nephropathy in patients with type 1 diabetes four years after a trial of intensive therapy. The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Research Group. N Engl J Med 2000; 342:381.
6. LaGasse, JM, Brantley, MS, Leech, NJ, et al. Successful prospective prediction of type 1 diabetes in schoolchildren through multiple defined autoantibodies: an 8-year follow-up of the Washington State Diabetes Prediction Study. Diabetes Care 2002; 25:505.
Elevated blood glucose levels (called hyperglycemia) cause a person to urinate more frequently, causing loss of body water and dehydration. A person can also feel tired and lose weight. In addition, a serious and potentially life-threatening complication known as diabetic ketoacidosis can develop (see "Symptoms" below). Long term complications associated with hyperglycemia can affect the eyes, nerves, kidneys, and cardiovascular system, leading to blindness, loss of sensation in the feet, the need for amputation of toes or a foot, kidney failure, and an increased risk of heart attack and stroke.
Type 1 diabetes requires regular blood glucose monitoring and treatment with insulin. Treatment, lifestyle adjustments, and self-care can effectively control blood glucose levels and minimize a person's risk of ketoacidosis and other disease-related complications.
Type 1 diabetes usually begins in childhood or young adulthood, but can develop at any age. In the United States, Canada, and Europe, type 1 diabetes accounts for 5 to 10 percent of all cases of diabetes. It is relatively more common in people who are white compared to people of African or Asian descent.
THE IMPACT OF DIABETES — Being diagnosed with type 1 diabetes can be a frightening and overwhelming experience for some patients, and it is common to have questions about why it developed, what it means for long-term health, and how it will affect everyday life. For most patients, the first few months after being diagnosed are filled with emotional highs and lows. Persons with newly-diagnosed diabetes, as well as their families, can use this time to learn as much as possible so that diabetes-related care (eg, self-blood glucose testing, medical appointments, daily insulin) becomes a "normal" part of the daily routine. (See "Patient information: Self-blood glucose monitoring").
In addition, persons who are newly diagnosed should talk to their healthcare provider about resources that are available for medical as well as psychological support. This may include group classes, meetings with a nutritionist, social worker, or nurse educator, and other educational resources such as books, web sites, or magazines. Several of these resources are listed in this topic review (see "Where to get more information" below).
Despite the risks associated with type 1 diabetes, most persons can lead active lives and continue to enjoy the foods and activities that they previously enjoyed. Diabetes does not mean an end to special occasion foods like birthday cake, and with a little advanced planning, most persons with diabetes can enjoy exercise in almost any form.
CAUSES — Type 1 diabetes usually develops when a person's immune system destroys the insulin-producing cells (called the beta cells) in the pancreas. This is called an autoimmune response. This process occurs over many months or years, during which a person has no signs or symptoms of diabetes. Hyperglycemia and its associated symptoms (frequent urination, thirst) do not usually occur until more than 90 percent of the beta cells have been destroyed, which greatly reduces insulin secretion. The cause of the abnormal immune response that destroys the beta cells is being actively studied.
Type 1 diabetes may develop in persons with a family history of type 1 diabetes, but may also develop in persons with no family history of diabetes. In either case, the person has one or more genes that make them susceptible to the disease. Environmental factors, such as exposure to certain viruses and foods early in life, may trigger the autoimmune response.
DIAGNOSIS — The diagnosis of diabetes is based upon a person's symptoms and the results of laboratory tests.
Symptoms — Most people have symptoms of high blood glucose levels (hyperglycemia) before being diagnosed with type 1 diabetes. These symptoms may include excessive thirst, fatigue, frequent urination, weight loss, or blurred vision.
Less commonly, a person will develop signs and symptoms of diabetic ketoacidosis (DKA) at the time of diagnosis. DKA causes symptoms of high blood glucose levels (see above), as well as nausea and vomiting, abdominal pain, rapid breathing, lethargy, decreased alertness, and sometimes coma. DKA is a medical emergency and must be treated promptly.
Rarely, type 1 diabetes is diagnosed before symptoms develop.
Laboratory tests — Several blood tests are used to measure blood glucose levels; this is the primary test for diagnosing diabetes. Additional tests can determine the type of diabetes and its severity. Random blood glucose test — For a random blood glucose test, blood can be drawn at any time throughout the day, regardless of when the person last ate. A random blood glucose level of 200 mg/dL (11.1 mmol/L) or higher in a person who has the typical symptoms of hyperglycemia suggests a diagnosis of diabetes. Fasting blood glucose test — Fasting blood glucose testing involves measurement of blood glucose after not eating or drinking for 8 to 12 hours (usually overnight). Fasting blood glucose is normally less than 100 mg/dL (5.6 mmol/L); values of 126 mg/dL (7.0 mmol/L) or higher suggests diabetes. However, the test must be repeated on another day to confirm the diagnosis of diabetes. Hemoglobin A1C test (A1C) — The A1C blood test measures the average blood glucose level during the past two to three months. It is used to monitor blood glucose control in people with known diabetes, but is not used to diagnose the disease. Normal values for A1C are usually 6.1 percent or lower (indicating an average blood glucose of 120 mg/dL [6.6 mmol/L], show figure 2). Most healthcare providers recommend measuring A1C three to four times per year in people with type 1 diabetes.
Criteria for diagnosis — The following criteria are used to define blood glucose levels as normal or indicative of diabetes. Normal — Fasting plasma glucose (FPG) <100 mg/dL (5.6 mmol/L). Diabetes mellitus — A person is diagnosed with diabetes if he or she has one or more of the following criteria:
- Symptoms of diabetes (see "Symptoms" above) and a fasting blood glucose level of 126 mg/dL (7.0 mmol/L) or higher
- Symptoms and a random blood glucose of 200 mg/dL (11.1 mmol/L) or higher
The blood tests must be repeated on another day to confirm that they remain abnormally high.
Type 1 versus type 2 diabetes — A healthcare provider is usually able to determine whether a patient has type 1 or type 2 diabetes based upon the need for insulin (which is needed from the beginning in type 1, and less commonly early in type 2), and the presence of ketones in the urine when blood glucose levels are elevated (common in type 1, uncommon in type 2). Other factors, such as age at diagnosis (generally younger for type 1), obesity (more common in type 2), and the presence of antibodies in the blood (present in type 1) can be used to distinguish between the two types. (See "Patient information: Diabetes mellitus, type 2").
However, there are situations where it is not clear if a person has type 1 or 2 diabetes. In this situation, a healthcare provider usually treats the patient as if they have type 1, since missing this diagnosis can result in DKA.
RISK FACTORS — A person whose parent or sibling has type 1 diabetes is at increased risk of developing the disease, compared to a person with no family history (5 to 6 percent versus 0.4 percent, respectively). To determine if a person with a family history of type 1 diabetes is at increased risk, genetic testing can be performed. Currently these tests are only available to those who participate in a clinical research trial. Persons who are found to be at risk for developing type 1 diabetes may be enrolled in further clinical trials aimed at preventing or delaying the disease from developing.
PREVENTION — Methods to prevent type 1 diabetes are still in the investigational stage. Currently, no treatment has been found to be effective in preventing type 1 diabetes for more than a brief period of time.
TREATMENT — Treatment of diabetes requires a team approach, including the patient and their family and healthcare providers (physician, nurse, diabetes educator, dietitian), and sometimes other clinicians (exercise physiologist, podiatrist, etc). The treatment of type 1 diabetes is discussed on a separate topic review. (See "Patient information: Diabetes type 1: Insulin treatment").
LONG-TERM OUTCOMES — Several studies have proven that persons with diabetes whose blood glucose levels are kept at near-normal levels can reduce their risk of long-term complications. In the Diabetes Control and Complications Trial, 1441 patients were followed for 6.5 years. Half the group used intensive insulin therapy (either with an insulin pump or three or more insulin injections daily) with the goal of maintaining glucose levels as close to the non-diabetic range as possible. The other half used conventional therapy (one to two insulin injections per day). Intensive therapy reduced the risk of retinopathy by 76 percent, nephropathy by 54 percent, and neuropathy by 60 percent [1]. Longer-term study of the DCCT population has shown that heart disease and strokes are also reduced with intensive diabetes therapy.
Thus, persons with diabetes can greatly reduce their risk of long-term complications by monitoring blood glucose levels frequently and using intensive insulin therapy. The goal A1C is as close to the non-diabetic range as possible and, at a minimum, should be less than 7 percent.
The life expectancy for persons with diabetes is based upon many factors, including the development of diabetes-related complications, lifestyle factors such as smoking, diet, exercise, and alcohol consumption, weight and other medical conditions.
COMPLICATIONS — Complications of type 1 diabetes are related to the disease itself as well as to the treatments that are necessary to manage diabetes. (See "Patient information: Preventing complications in diabetes mellitus").
Disease-related complications — Persons with type 1 diabetes are at increased risk of cardiovascular disease, which can cause myocardial infarction (heart attack), angina (chest pain), stroke, and death. The risk is estimated to be at least twice that of nondiabetics. However, persons with type 1 diabetes can substantially lower their risk of cardiovascular disease by not smoking, taking a low-dose aspirin every day (for adults only), and by managing high blood pressure and hyperlipidemia with diet, exercise, and medications, and by achieving an A1C level of 7 percent or lower. (See "Patient information: High cholesterol and lipids (hyperlipidemia)" and see "Patient information: High blood pressure treatment" and see "Patient information: Smoking cessation" and see "Patient information: Aspirin and heart disease").
The more specific complications of type 1 diabetes include damage to small blood vessels (called microvascular damage) and nerves. This damage is the result of elevated blood glucose levels over a period of many years; improving blood glucose control can prevent or reduce the risk of these complications.
Microvascular damage affects the retina in the eyes (the light-sensitive film in the back of the eyes). This is called retinopathy, which can lead to decreased vision or blindness. Microvascular damage also affects the kidneys (called nephropathy, which can lead to kidney failure), and nerves (called neuropathy, which can cause pain and increases the risk of foot injury and infection). The risk of nephropathy, neuropathy, and retinopathy is related to the level of the A1C; the higher the A1C value, the greater the risk (show figure 3 and show figure 4). Other factors, especially high blood pressure, increase the risk of diabetic complications. (See "Patient information: Foot care in diabetes").
Treatment-related complications — Treatment-related complications of type 1 diabetes are more common in persons who use intensive insulin therapy. Intensive insulin therapy involves giving three or more insulin injections daily, or use of an insulin pump. Complications of this type of treatment can include hypoglycemia (low blood sugar) and weight gain. However, intensive insulin therapy has significant benefits despite these treatment-related risks. (See "Patient information: Diabetes type 1: Insulin treatment").
Results from a large trial demonstrated that the risk of hypoglycemia increased as the A1C was lowered. However, there is wide variability in the rate of hypoglycemia for a given A1C value. Thus, each patient must find his or her own level of tolerance. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
Weight gain is also a common problem with intensive insulin regimens. Weight gain can be prevented or managed with regular exercise and careful attention to diet.
PREGNANCY AND DIABETES — Women with type 1 diabetes are usually able to become pregnant and have a healthy baby. However, it is important to tightly control blood glucose levels before and during pregnancy to minimize the risk of complications. A full discussion of this topic is available separately. (See "Patient information: Care during pregnancy for women with type 1 or 2 diabetes").
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-6]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. The Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993; 329:977.
2. Alberti, KG, Zimmet, PZ for the WHO Consultation. Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: Diagnosis and classification of diabetes mellitus. Provisional report of a WHO consultation. Diabet Med 1998; 15:539.
3. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care 1997; 20:1183.
4. Nathan, DM, Cleary, PA, Backlund, JY, et al. Intensive diabetes treatment and cardiovascular disease in patients with type 1 diabetes. N Engl J Med 2005; 353:2643.
5. Retinopathy and nephropathy in patients with type 1 diabetes four years after a trial of intensive therapy. The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Research Group. N Engl J Med 2000; 342:381.
6. LaGasse, JM, Brantley, MS, Leech, NJ, et al. Successful prospective prediction of type 1 diabetes in schoolchildren through multiple defined autoantibodies: an 8-year follow-up of the Washington State Diabetes Prediction Study. Diabetes Care 2002; 25:505.
Care during pregnancy for women with type 1 or 2 diabetes
INTRODUCTION — Prior to the development of insulin in 1922, pregnancy in women with diabetes mellitus posed very high risks to both mother and fetus. Today, most women with diabetes can expect an excellent pregnancy outcome, similar to that of nondiabetic women. This improvement is largely due to better blood glucose control, which can be achieved with frequent daily glucose monitoring and insulin adjustment.
This topic review discusses care of women with type 1 or 2 diabetes during pregnancy, as well as fetal and newborn issues. It does not address gestational diabetes, which develops during pregnancy.
BLOOD GLUCOSE MANAGEMENT — High blood glucose levels early in pregnancy (especially a A1C above 8 percent or average blood glucose above 180 mg/dL (10 mmol/L)) increases the risk of miscarriage (show table 1). A1C is a blood test that measures the average blood glucose level. High blood glucose levels (eg, average blood glucose level of 180 mg/dL (10 mmol/L) or higher) in the last half of pregnancy and near delivery can cause the infant to be larger than normal (see "Ultrasound" below) and be at higher risk for complications after delivery (see "Newborn issues" below). Women with large infants are more likely to have a difficult vaginal birth or require delivery by cesarean section. Very high blood glucose levels (over 250 mg/dL (13.9 mmol/L)) late in pregnancy increases the risk of stillbirth. These complications occur less frequently when blood glucose levels are carefully controlled.
Glucose in the mother's blood crosses the placenta to help provide energy for the fetus; thus, maternal hyperglycemia (high blood glucose levels) leads to fetal hyperglycemia as well. In response to high glucose levels, the fetus produces large amounts of insulin, which lead to problems such as excessive fetal growth and low blood glucose levels after birth (see "Planning for delivery" below).
General measures Two to four insulin injections per day are recommended. Alternately, patients can use an insulin pump. For women with type 2 diabetes, insulin is not always required during pregnancy; when it is required, two injections per day will often provide acceptable blood gluose control. Women with diabetes need more insulin during pregnancy, especially during the last one-third of pregnancy (approximately 26 to 40 weeks of gestation) because the body becomes resistant to the actions of insulin as the pregnancy progresses. (See "Patient information: Diabetes type 1: Insulin treatment"). Frequent contact with health care providers is important for managing blood glucose levels and monitoring maternal and fetal health. The healthcare provider may want to review blood glucose levels and insulin doses one or more times per week; this can usually be done via telephone, e-mail, or fax. Oral hypoglycemic agents, specifically glyburide, have been used to manage gestational or type 2 diabetes in some women. These medications adequately control blood glucose levels, but large studies of their safety have not been performed. As a result, the American College of Obstetricians and Gynecologists and American Diabetes Association do not recommended their use during pregnancy at this time. Women who are taking these drugs when they become pregnant should speak with their healthcare provider. A nutritionist can help to plan a diet that provides the optimal number of calories, carbohydrate content, and distribution of snacks/meals throughout the day. The optimal calorie intake depends upon the woman's prepregnancy weight and activity level. Exercise is an excellent way to control weight and blood glucose levels. Most women who exercised before pregnancy can continue to do so during pregnancy at the same or a slightly reduced pace. Moderate intensity exercise, such as brisk walking, is recommended. Women who did not exercise previously may begin to exercise during pregnancy after consulting with their healthcare provider. Exercise intensity, type, and duration may need to be modified as the pregnancy progresses or if complications develop.
Target blood glucose levels — Frequent glucose monitoring is recommended during pregnancy, including testing before breakfast (while fasting) and before and after each meal. (See "Patient information: Self-blood glucose monitoring"). Target blood glucose levels during pregnancy are slightly lower than for persons with diabetes who are not pregnant. Goals are as follows: Fasting: 60 to 90 mg/dL (3.3 to 5 mmol/L) Preprandial (before meals): less than 100 mg/dL (5.5 mmol/L) One-hour postprandial (after meals): less than 130 to 140 mg/dL (7.2 to 7.7 mmol/L) Two-hour postprandial: less than 120 mg/dL (6.7 mmol/L)
A1C is usually done every four to six weeks. A1C at or near 6 percent (which corresponds to an average blood glucose of 120 mg/dL (6.7 mmol/L)) is recommended during pregnancy (show table 1). However, attempting to maintain this level can result in frequent episodes of hypoglycemia (low blood glucose), so A1C goals should be determined individually. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
CARE DURING PREGNANCY — The care of diabetic women during pregnancy is a team effort involving an obstetrician and an endocrinologist or internist who oversees insulin management and medical care. Ideally, care should begin before a woman becomes pregnant so that medications can be adjusted if needed, folic acid supplementation can be started (at least 400 mcg per day is recommended, starting before conception) and other genetic issues may be fully addressed (show table 2). A summary of the testing recommended during pregnancy is shown in the table (show table 3).
Eye examination — Retinopathy causes abnormal, leaky blood vessels in the retina, the light sensitive tissue lining the back of the eye. Retinopathy can lead to vision problems, and even blindness in severe cases. Pregnancy can worsen diabetic retinopathy due to rapidly lowered blood glucose levels; which may occur when a person begins more frequent blood glucose monitoring and control measures. Changes in hormones, blood pressure, and blood flow in the retinal artery can also worsen retinopathy.
Thus, pregnant women with type 1 or 2 diabetes should have an eye examination by an ophthalmologist or optometrist during the first trimester (three months) of their pregnancy. Subsequent eye examinations during the pregnancy may be needed, depending upon the results of the initial examination. In most cases, eye examination is recommended every three months until delivery.
The impact of pregnancy on diabetic retinopathy is mild and temporary for most women; the retina usually returns to its prepregnancy condition within several months postpartum. Patients with severe retinopathy are more likely to experience progression and complications. Eye examinations before and during pregnancy, along with close monitoring and treatment (as needed) of retinopathy can minimize the risk of vision loss. Some experts have recommended cesarean delivery for women with retinopathy, although this is controversial; most women can attempt a vaginal delivery.
Blood pressure monitoring — Blood pressure may become elevated during pregnancy and should be measured frequently during visits with a diabetes specialist or obstetrician.
Gestational hypertension (high blood pressure during pregnancy) and preeclampsia are more common in women with diabetes. Blood pressure often improves in the first half of pregnancy, but returns to baseline or worsens in the second half. Medications to treat high blood pressure during pregnancy include methyldopa, calcium channel blocking agents, hydralazine, or beta blockers. However, angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are not safe during pregnancy.
Preeclampsia is a condition that can occur in pregnancy that causes hypertension (blood pressure greater than 140/90) and proteinuria (protein in the urine). Fortunately, most cases are mild. In severe cases (eclampsia), seizure, stroke, heart failure, kidney damage, and rarely, maternal death can occur. Preeclampsia cannot be prevented; the only treatment is delivery of the baby. Women with moderately elevated blood pressure monitored for days or even weeks if preeclampsia develops prematurely; this may require hospitalization. Corticosteroids may be given to encourage the fetus's lungs to mature more rapidly. Steroids can significantly raise the mother's blood glucose levels, which requires a temporary increase in the insulin dose. (See "Patient information: Preeclampsia").
Kidney function monitoring — Pregnancy does not cause diabetes-related kidney disease (nephropathy), but it can worsen existing disease. Kidney function is monitored during pregnancy by urine dipstick testing for protein, which is usually performed at every visit. Other urine or blood tests may be ordered depending upon the individual's situation.
Nephropathy can cause other pregnancy complications, such as preeclampsia, preterm delivery, babies who are small for their age (intrauterine growth restriction (IUGR)), and a higher frequency of maternal hospitalization and cesarean delivery (show table 4). Women with retinopathy and kidney disease are at increased risk of having a small infant because blood flow to the placenta may be reduced.
If a woman develops worsening nephropathy during pregnancy, it is usually temporary and reverts to the prepregnancy condition within several months of delivery. Worsening nephropathy probably occurs because blood flow through the kidney increases by 50 percent during pregnancy, which increases the kidneys' workload. In addition, some women develop worsening hypertension or new pregnancy-induced hypertension, which further stresses the kidney.
Permanent kidney damage, including kidney failure, can occur, and is more common among women who have poorly controlled blood pressure or a serum creatinine (a blood test of kidney function) of 1.5 mg/dL or greater at the beginning of pregnancy. These women may require dialysis or kidney transplant sooner than a woman with severe chronic kidney disease who never becomes pregnant. (See "Patient information: Renal replacement therapy" and see "Patient information: Hemodialysis").
Ultrasound — Ultrasound examination of the fetus is recommended during the first trimester (before 13 weeks) if there is any uncertainty about the last menstrual period date or estimated due date. It is important that the due date is accurate because decisions about when to begin fetal testing and when to deliver the baby are based upon this date.
Ultrasound examination is recommended at 18 to 20 weeks gestation to screen for birth defects, and some experts recommend a fetal echocardiogram (an ultrasound of the fetus's heart) because of the increased incidence of heart defects among infants of diabetic mothers.
Ultrasound is also used to monitor the amount of amniotic fluid around the fetus; polyhydramnios is an abnormal increase in the amount of amniotic fluid. This condition is more common in women with diabetes than in women without diabetes. Polyhydramnios related to diabetes is usually mild and does not cause problems. If it becomes severe, maternal discomfort, uterine contractions, premature rupture of the membranes ("breaking the water"), and preterm delivery can occur. (See "Patient information: Preterm labor").
Ultrasound is also used to monitor the fetus's growth and development throughout the pregnancy. Macrosomia is a condition in which an infant weighs more than nine pounds or 4000 grams at term (at or beyond 37 weeks of pregnancy), and is more common in women with diabetes. High fetal insulin levels, which can develop in response to elevated maternal blood glucose levels, contribute to an infant's weight since insulin stimulates fetal growth.
Macrosomia occurs in 15 to 45 percent of diabetic pregnancies, compared to 10 percent in the nondiabetic population. Macrosomic infants are at higher risk of being injured during delivery and are more likely to require cesarean delivery because the infant's shoulders may be difficult to deliver through a woman's pelvis (called shoulder dystocia). Shoulder dystocia occurs in 1 out of 4 macrosomic births in women with diabetes (show table 5).
Screening for birth defects — Birth defects are more common in women with elevated blood glucose levels before and during the early weeks of pregnancy. There is no particular birth defect caused by maternal diabetes, though most occur by the seventh week of pregnancy. In older studies, the frequency of birth defects was approximately 8 to 13 percent among diabetic women, compared to 2 to 4 percent in the nondiabetic population. However, more recent studies have demonstrated that tight blood glucose control prior to becoming pregnant greatly reduces the risk of birth defects to a level similar to women who do not have diabetes.
First or second trimester screening for birth defects such as spina bifida and Down syndrome is recommended (to all women, not just those with diabetes). Women with diabetes are not at increased risk for having a baby with a chromosomal abnormality, such as Down's syndrome, but they are at increased risk of having a baby with a neural tube defect (eg, spina bifda). These tests are used for screening (as opposed to diagnosis), and cannot determine with certainty if a baby has these problems. If the test is abnormal, an ultrasound examination and/or amniocentesis may be performed to determine if the abnormality is actually present. (See "Patient information: First trimester and integrated screening for Down syndrome" and see "Patient information: Second trimester screening for Down syndrome" and see "Patient information: Amniocentesis").
Fetal testing — Close monitoring of the fetus is recommended in the third trimester, including weekly to twice-weekly nonstress testing. This is done by monitoring the baby's heart rate with a small device that is placed on the mother's abdomen. The device uses sound waves (ultrasound) to measure the baby's heart rate over time, usually for 20 to 30 minutes. Normally, the baby's baseline heart rate should be between 110 and 160 beats per minute and should increase above its baseline by at least 15 beats per minute for 15 seconds when the baby moves.
The test is considered reassuring (called "reactive") if two or more fetal heart rate increases are seen within a 20 minute period. Further testing may be needed if these increases are not observed after monitoring for 40 minutes.
PLANNING FOR DELIVERY — A woman and her obstetrician may decide to schedule the date of her delivery (either an induction of labor or Cesarean section), especially if there are risk factors, such as poor blood glucose levels, nephropathy, worsening retinopathy, hypertension or preeclampsia, or limited or excessive fetal growth. If delivery before the due date is planned, an amniocentesis to determine fetal lung maturity may be needed, depending on the individual's situation and the fetus's gestational age. (See "Patient information: Amniocentesis").
If the fetus appears to be very large (based upon ultrasound measurements), a woman and her obstetrician should consider cesarean delivery to avoid possible trauma from shoulder dystocia. The American College of Obstetricians and Gynecologists recommends that a woman and her physician consider a planned Cesarean delivery if the estimated fetal weight (by ultrasound measurement) is greater than 4500 grams (9 lbs, 14 oz).
Waiting for labor to start on its own is reasonable if blood glucose levels are well-controlled and the mother and fetus are without problems. However, extending pregnancy beyond 40 to 41 weeks of gestation is generally not recommended; some practitioners routinely induce labor between 39 and 40 weeks in all women with type 1 or 2 diabetes.
The risk of stillbirth for pregnant women with carefully controlled diabetes is about the same as women without diabetes: less than 1 percent. The newborn mortality (death) rate in infants of diabetic women is slightly higher than in nondiabetics (2 versus 1 percent). This is due to a higher rate of serious birth defects, premature births, and breathing problems (respiratory distress syndrome) in infants of diabetic mothers.
INFANT CARE
Newborn issues — The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood glucose levels (less than 30 mg/dL (1.7 mmol/L)), jaundice, breathing problems, too many red blood cells (polycythemia), low calcium level, and heart problems. These problems are more common when the mother's blood glucose levels have been elevated during the pregnancy. Most of these problems resolve within a few hours or days of delivery. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems.
Infants of mothers with diabetes are at higher risk of breathing difficulties, especially if the infant is born earlier than 39 weeks of gestation. This is due to a delay in lung maturation, which appears to be more common in infants of women with diabetes. The risk of respiratory problems is highest when maternal blood glucose levels have been elevated near the time of delivery.
Inheritance of diabetes — The children of diabetic parents have a higher risk for developing the same type of diabetes. In one study, the risk of type 1 diabetes in the child was 1.3 percent (if the mother was diabetic) or 6.1 percent (if the father was diabetic). The risk of type 2 diabetes in children is 10 to 15 times higher (than children of nondiabetic parents) if one parent has type 2 diabetes. (See "Patient information: Diabetes mellitus, type 1" and see "Patient information: Diabetes mellitus, type 2").
AFTER DELIVERY CARE — Postpartum (after delivery) care for a woman with diabetes is similar to that for women without diabetes. However, it is important to pay close attention to blood glucose levels because insulin requirements are highly variable in the immediate postpartum period; some women require little or no insulin. Insulin requirements usually return to near-prepregnancy levels within 48 hours.
Breastfeeding — Breastfeeding is strongly encouraged, and benefits both the infant and the mother. Insulin requirements may be lower while breastfeeding, and frequent blood glucose monitoring is important to prevent severe hypoglycemia. Approximately 400 additional calories are required each day while breastfeeding. Breastfeeding for longer than three months can aid in maternal weight loss and provides significant short and long-term benefits to the infant.
Adequate amounts of human milk meet all the nutritional requirements of an infant during the first six months of life. Exclusive breastfeeding (without formula supplementation) is recommended for the first six months after birth, and partial breastfeeding is recommended for at least 12 months, and thereafter for as long as mutually desired. The World Health Organization recommends that partial breastfeeding continue for up to two years, and beyond.
SUMMARY Most women with diabetes can expect an excellent pregnancy outcome as a result of improvements in blood glucose control; this requires frequent daily glucose testing and insulin adjustment. Women with diabetes who have elevated blood glucose levels before or during pregnancy are more likely to have complications, including miscarriage, stillbirth, a large baby that requires cesarean delivery, or worsening of existing kidney function or retinopathy. Frequent visits with a healthcare provider are recommended to monitor blood glucose levels and blood pressure, eye and kidney health, and also to monitor the health of the developing baby. Target blood glucose levels during pregnancy are as follows: A!C level: less than 6 (show table 1), fasting blood glucose: 60 to 90 mg/dL (3.3 to 5 mmol/L), before meals: less than 100 mg/dL (5.5 mmol/L), one hour after meals: less than 130 to 140 mg/dL (7.2 to 7.7 mmol/L), two-hours after meals: less than 120 mg/dL (6.7 mmol/L). A woman and her obstetrician may decide to schedule the date of her delivery (either an induction of labor or Cesarean section), especially if there are risk factors, such as poor blood glucose levels, nephropathy, worsening retinopathy, hypertension or preeclampsia, or limited or excessive fetal growth. Waiting for labor to start on its own is reasonable if blood glucose levels are well-controlled and the mother and fetus are without problems. However, extending pregnancy beyond 40 to 41 weeks of gestation is generally not recommended If the fetus appears to be very large (based upon ultrasound measurements), a woman and her obstetrician should consider cesarean delivery to avoid possible trauma from shoulder dystocia. The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood glucose levels (less than 30 mg/dL [1.7 mmol/L]), jaundice, too many red blood cells (polycythemia), low calcium level, and heart problems. These problems are more common when the mother's blood glucose levels have been elevated during the pregnancy. Most of these problems resolve within a few hours or days of delivery. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems. Postpartum (after delivery) care for a woman with diabetes is similar to that for women without diabetes. However, insulin requirements are highly variable in the immediate postpartum period; some women require little or no insulin. Insulin requirements usually return to near-prepregnancy levels within 48 hours. Breastfeeding is strongly encouraged, and benefits both the infant and the mother. Insulin requirements may be lower while breastfeeding, and frequent blood glucose monitoring is important to prevent severe hypoglycemia. Approximately 400 additional calories are required each day while breastfeeding. Breastfeeding for longer than three months can aid in maternal weight loss and provides significant short and long-term benefits to the infant.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov/)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-4]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Diabetes mellitus in pregnancy. Obstet Gynecol Clin North Am Dec 2004.
2. Bernasko, J. Contemporary management of type 1 diabetes mellitus in pregnancy. Obstet Gynecol Surv 2004; 59:628.
3. Preconception care of women with diabetes. Diabetes Care 2004; 27 Suppl 1:S76.
4. Gabbe, SG, Graves, CR. Management of diabetes mellitus complicating pregnancy. Obstet Gynecol 2003; 102:857.
This topic review discusses care of women with type 1 or 2 diabetes during pregnancy, as well as fetal and newborn issues. It does not address gestational diabetes, which develops during pregnancy.
BLOOD GLUCOSE MANAGEMENT — High blood glucose levels early in pregnancy (especially a A1C above 8 percent or average blood glucose above 180 mg/dL (10 mmol/L)) increases the risk of miscarriage (show table 1). A1C is a blood test that measures the average blood glucose level. High blood glucose levels (eg, average blood glucose level of 180 mg/dL (10 mmol/L) or higher) in the last half of pregnancy and near delivery can cause the infant to be larger than normal (see "Ultrasound" below) and be at higher risk for complications after delivery (see "Newborn issues" below). Women with large infants are more likely to have a difficult vaginal birth or require delivery by cesarean section. Very high blood glucose levels (over 250 mg/dL (13.9 mmol/L)) late in pregnancy increases the risk of stillbirth. These complications occur less frequently when blood glucose levels are carefully controlled.
Glucose in the mother's blood crosses the placenta to help provide energy for the fetus; thus, maternal hyperglycemia (high blood glucose levels) leads to fetal hyperglycemia as well. In response to high glucose levels, the fetus produces large amounts of insulin, which lead to problems such as excessive fetal growth and low blood glucose levels after birth (see "Planning for delivery" below).
General measures Two to four insulin injections per day are recommended. Alternately, patients can use an insulin pump. For women with type 2 diabetes, insulin is not always required during pregnancy; when it is required, two injections per day will often provide acceptable blood gluose control. Women with diabetes need more insulin during pregnancy, especially during the last one-third of pregnancy (approximately 26 to 40 weeks of gestation) because the body becomes resistant to the actions of insulin as the pregnancy progresses. (See "Patient information: Diabetes type 1: Insulin treatment"). Frequent contact with health care providers is important for managing blood glucose levels and monitoring maternal and fetal health. The healthcare provider may want to review blood glucose levels and insulin doses one or more times per week; this can usually be done via telephone, e-mail, or fax. Oral hypoglycemic agents, specifically glyburide, have been used to manage gestational or type 2 diabetes in some women. These medications adequately control blood glucose levels, but large studies of their safety have not been performed. As a result, the American College of Obstetricians and Gynecologists and American Diabetes Association do not recommended their use during pregnancy at this time. Women who are taking these drugs when they become pregnant should speak with their healthcare provider. A nutritionist can help to plan a diet that provides the optimal number of calories, carbohydrate content, and distribution of snacks/meals throughout the day. The optimal calorie intake depends upon the woman's prepregnancy weight and activity level. Exercise is an excellent way to control weight and blood glucose levels. Most women who exercised before pregnancy can continue to do so during pregnancy at the same or a slightly reduced pace. Moderate intensity exercise, such as brisk walking, is recommended. Women who did not exercise previously may begin to exercise during pregnancy after consulting with their healthcare provider. Exercise intensity, type, and duration may need to be modified as the pregnancy progresses or if complications develop.
Target blood glucose levels — Frequent glucose monitoring is recommended during pregnancy, including testing before breakfast (while fasting) and before and after each meal. (See "Patient information: Self-blood glucose monitoring"). Target blood glucose levels during pregnancy are slightly lower than for persons with diabetes who are not pregnant. Goals are as follows: Fasting: 60 to 90 mg/dL (3.3 to 5 mmol/L) Preprandial (before meals): less than 100 mg/dL (5.5 mmol/L) One-hour postprandial (after meals): less than 130 to 140 mg/dL (7.2 to 7.7 mmol/L) Two-hour postprandial: less than 120 mg/dL (6.7 mmol/L)
A1C is usually done every four to six weeks. A1C at or near 6 percent (which corresponds to an average blood glucose of 120 mg/dL (6.7 mmol/L)) is recommended during pregnancy (show table 1). However, attempting to maintain this level can result in frequent episodes of hypoglycemia (low blood glucose), so A1C goals should be determined individually. (See "Patient information: Hypoglycemia (low blood glucose) in diabetes").
CARE DURING PREGNANCY — The care of diabetic women during pregnancy is a team effort involving an obstetrician and an endocrinologist or internist who oversees insulin management and medical care. Ideally, care should begin before a woman becomes pregnant so that medications can be adjusted if needed, folic acid supplementation can be started (at least 400 mcg per day is recommended, starting before conception) and other genetic issues may be fully addressed (show table 2). A summary of the testing recommended during pregnancy is shown in the table (show table 3).
Eye examination — Retinopathy causes abnormal, leaky blood vessels in the retina, the light sensitive tissue lining the back of the eye. Retinopathy can lead to vision problems, and even blindness in severe cases. Pregnancy can worsen diabetic retinopathy due to rapidly lowered blood glucose levels; which may occur when a person begins more frequent blood glucose monitoring and control measures. Changes in hormones, blood pressure, and blood flow in the retinal artery can also worsen retinopathy.
Thus, pregnant women with type 1 or 2 diabetes should have an eye examination by an ophthalmologist or optometrist during the first trimester (three months) of their pregnancy. Subsequent eye examinations during the pregnancy may be needed, depending upon the results of the initial examination. In most cases, eye examination is recommended every three months until delivery.
The impact of pregnancy on diabetic retinopathy is mild and temporary for most women; the retina usually returns to its prepregnancy condition within several months postpartum. Patients with severe retinopathy are more likely to experience progression and complications. Eye examinations before and during pregnancy, along with close monitoring and treatment (as needed) of retinopathy can minimize the risk of vision loss. Some experts have recommended cesarean delivery for women with retinopathy, although this is controversial; most women can attempt a vaginal delivery.
Blood pressure monitoring — Blood pressure may become elevated during pregnancy and should be measured frequently during visits with a diabetes specialist or obstetrician.
Gestational hypertension (high blood pressure during pregnancy) and preeclampsia are more common in women with diabetes. Blood pressure often improves in the first half of pregnancy, but returns to baseline or worsens in the second half. Medications to treat high blood pressure during pregnancy include methyldopa, calcium channel blocking agents, hydralazine, or beta blockers. However, angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are not safe during pregnancy.
Preeclampsia is a condition that can occur in pregnancy that causes hypertension (blood pressure greater than 140/90) and proteinuria (protein in the urine). Fortunately, most cases are mild. In severe cases (eclampsia), seizure, stroke, heart failure, kidney damage, and rarely, maternal death can occur. Preeclampsia cannot be prevented; the only treatment is delivery of the baby. Women with moderately elevated blood pressure monitored for days or even weeks if preeclampsia develops prematurely; this may require hospitalization. Corticosteroids may be given to encourage the fetus's lungs to mature more rapidly. Steroids can significantly raise the mother's blood glucose levels, which requires a temporary increase in the insulin dose. (See "Patient information: Preeclampsia").
Kidney function monitoring — Pregnancy does not cause diabetes-related kidney disease (nephropathy), but it can worsen existing disease. Kidney function is monitored during pregnancy by urine dipstick testing for protein, which is usually performed at every visit. Other urine or blood tests may be ordered depending upon the individual's situation.
Nephropathy can cause other pregnancy complications, such as preeclampsia, preterm delivery, babies who are small for their age (intrauterine growth restriction (IUGR)), and a higher frequency of maternal hospitalization and cesarean delivery (show table 4). Women with retinopathy and kidney disease are at increased risk of having a small infant because blood flow to the placenta may be reduced.
If a woman develops worsening nephropathy during pregnancy, it is usually temporary and reverts to the prepregnancy condition within several months of delivery. Worsening nephropathy probably occurs because blood flow through the kidney increases by 50 percent during pregnancy, which increases the kidneys' workload. In addition, some women develop worsening hypertension or new pregnancy-induced hypertension, which further stresses the kidney.
Permanent kidney damage, including kidney failure, can occur, and is more common among women who have poorly controlled blood pressure or a serum creatinine (a blood test of kidney function) of 1.5 mg/dL or greater at the beginning of pregnancy. These women may require dialysis or kidney transplant sooner than a woman with severe chronic kidney disease who never becomes pregnant. (See "Patient information: Renal replacement therapy" and see "Patient information: Hemodialysis").
Ultrasound — Ultrasound examination of the fetus is recommended during the first trimester (before 13 weeks) if there is any uncertainty about the last menstrual period date or estimated due date. It is important that the due date is accurate because decisions about when to begin fetal testing and when to deliver the baby are based upon this date.
Ultrasound examination is recommended at 18 to 20 weeks gestation to screen for birth defects, and some experts recommend a fetal echocardiogram (an ultrasound of the fetus's heart) because of the increased incidence of heart defects among infants of diabetic mothers.
Ultrasound is also used to monitor the amount of amniotic fluid around the fetus; polyhydramnios is an abnormal increase in the amount of amniotic fluid. This condition is more common in women with diabetes than in women without diabetes. Polyhydramnios related to diabetes is usually mild and does not cause problems. If it becomes severe, maternal discomfort, uterine contractions, premature rupture of the membranes ("breaking the water"), and preterm delivery can occur. (See "Patient information: Preterm labor").
Ultrasound is also used to monitor the fetus's growth and development throughout the pregnancy. Macrosomia is a condition in which an infant weighs more than nine pounds or 4000 grams at term (at or beyond 37 weeks of pregnancy), and is more common in women with diabetes. High fetal insulin levels, which can develop in response to elevated maternal blood glucose levels, contribute to an infant's weight since insulin stimulates fetal growth.
Macrosomia occurs in 15 to 45 percent of diabetic pregnancies, compared to 10 percent in the nondiabetic population. Macrosomic infants are at higher risk of being injured during delivery and are more likely to require cesarean delivery because the infant's shoulders may be difficult to deliver through a woman's pelvis (called shoulder dystocia). Shoulder dystocia occurs in 1 out of 4 macrosomic births in women with diabetes (show table 5).
Screening for birth defects — Birth defects are more common in women with elevated blood glucose levels before and during the early weeks of pregnancy. There is no particular birth defect caused by maternal diabetes, though most occur by the seventh week of pregnancy. In older studies, the frequency of birth defects was approximately 8 to 13 percent among diabetic women, compared to 2 to 4 percent in the nondiabetic population. However, more recent studies have demonstrated that tight blood glucose control prior to becoming pregnant greatly reduces the risk of birth defects to a level similar to women who do not have diabetes.
First or second trimester screening for birth defects such as spina bifida and Down syndrome is recommended (to all women, not just those with diabetes). Women with diabetes are not at increased risk for having a baby with a chromosomal abnormality, such as Down's syndrome, but they are at increased risk of having a baby with a neural tube defect (eg, spina bifda). These tests are used for screening (as opposed to diagnosis), and cannot determine with certainty if a baby has these problems. If the test is abnormal, an ultrasound examination and/or amniocentesis may be performed to determine if the abnormality is actually present. (See "Patient information: First trimester and integrated screening for Down syndrome" and see "Patient information: Second trimester screening for Down syndrome" and see "Patient information: Amniocentesis").
Fetal testing — Close monitoring of the fetus is recommended in the third trimester, including weekly to twice-weekly nonstress testing. This is done by monitoring the baby's heart rate with a small device that is placed on the mother's abdomen. The device uses sound waves (ultrasound) to measure the baby's heart rate over time, usually for 20 to 30 minutes. Normally, the baby's baseline heart rate should be between 110 and 160 beats per minute and should increase above its baseline by at least 15 beats per minute for 15 seconds when the baby moves.
The test is considered reassuring (called "reactive") if two or more fetal heart rate increases are seen within a 20 minute period. Further testing may be needed if these increases are not observed after monitoring for 40 minutes.
PLANNING FOR DELIVERY — A woman and her obstetrician may decide to schedule the date of her delivery (either an induction of labor or Cesarean section), especially if there are risk factors, such as poor blood glucose levels, nephropathy, worsening retinopathy, hypertension or preeclampsia, or limited or excessive fetal growth. If delivery before the due date is planned, an amniocentesis to determine fetal lung maturity may be needed, depending on the individual's situation and the fetus's gestational age. (See "Patient information: Amniocentesis").
If the fetus appears to be very large (based upon ultrasound measurements), a woman and her obstetrician should consider cesarean delivery to avoid possible trauma from shoulder dystocia. The American College of Obstetricians and Gynecologists recommends that a woman and her physician consider a planned Cesarean delivery if the estimated fetal weight (by ultrasound measurement) is greater than 4500 grams (9 lbs, 14 oz).
Waiting for labor to start on its own is reasonable if blood glucose levels are well-controlled and the mother and fetus are without problems. However, extending pregnancy beyond 40 to 41 weeks of gestation is generally not recommended; some practitioners routinely induce labor between 39 and 40 weeks in all women with type 1 or 2 diabetes.
The risk of stillbirth for pregnant women with carefully controlled diabetes is about the same as women without diabetes: less than 1 percent. The newborn mortality (death) rate in infants of diabetic women is slightly higher than in nondiabetics (2 versus 1 percent). This is due to a higher rate of serious birth defects, premature births, and breathing problems (respiratory distress syndrome) in infants of diabetic mothers.
INFANT CARE
Newborn issues — The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood glucose levels (less than 30 mg/dL (1.7 mmol/L)), jaundice, breathing problems, too many red blood cells (polycythemia), low calcium level, and heart problems. These problems are more common when the mother's blood glucose levels have been elevated during the pregnancy. Most of these problems resolve within a few hours or days of delivery. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems.
Infants of mothers with diabetes are at higher risk of breathing difficulties, especially if the infant is born earlier than 39 weeks of gestation. This is due to a delay in lung maturation, which appears to be more common in infants of women with diabetes. The risk of respiratory problems is highest when maternal blood glucose levels have been elevated near the time of delivery.
Inheritance of diabetes — The children of diabetic parents have a higher risk for developing the same type of diabetes. In one study, the risk of type 1 diabetes in the child was 1.3 percent (if the mother was diabetic) or 6.1 percent (if the father was diabetic). The risk of type 2 diabetes in children is 10 to 15 times higher (than children of nondiabetic parents) if one parent has type 2 diabetes. (See "Patient information: Diabetes mellitus, type 1" and see "Patient information: Diabetes mellitus, type 2").
AFTER DELIVERY CARE — Postpartum (after delivery) care for a woman with diabetes is similar to that for women without diabetes. However, it is important to pay close attention to blood glucose levels because insulin requirements are highly variable in the immediate postpartum period; some women require little or no insulin. Insulin requirements usually return to near-prepregnancy levels within 48 hours.
Breastfeeding — Breastfeeding is strongly encouraged, and benefits both the infant and the mother. Insulin requirements may be lower while breastfeeding, and frequent blood glucose monitoring is important to prevent severe hypoglycemia. Approximately 400 additional calories are required each day while breastfeeding. Breastfeeding for longer than three months can aid in maternal weight loss and provides significant short and long-term benefits to the infant.
Adequate amounts of human milk meet all the nutritional requirements of an infant during the first six months of life. Exclusive breastfeeding (without formula supplementation) is recommended for the first six months after birth, and partial breastfeeding is recommended for at least 12 months, and thereafter for as long as mutually desired. The World Health Organization recommends that partial breastfeeding continue for up to two years, and beyond.
SUMMARY Most women with diabetes can expect an excellent pregnancy outcome as a result of improvements in blood glucose control; this requires frequent daily glucose testing and insulin adjustment. Women with diabetes who have elevated blood glucose levels before or during pregnancy are more likely to have complications, including miscarriage, stillbirth, a large baby that requires cesarean delivery, or worsening of existing kidney function or retinopathy. Frequent visits with a healthcare provider are recommended to monitor blood glucose levels and blood pressure, eye and kidney health, and also to monitor the health of the developing baby. Target blood glucose levels during pregnancy are as follows: A!C level: less than 6 (show table 1), fasting blood glucose: 60 to 90 mg/dL (3.3 to 5 mmol/L), before meals: less than 100 mg/dL (5.5 mmol/L), one hour after meals: less than 130 to 140 mg/dL (7.2 to 7.7 mmol/L), two-hours after meals: less than 120 mg/dL (6.7 mmol/L). A woman and her obstetrician may decide to schedule the date of her delivery (either an induction of labor or Cesarean section), especially if there are risk factors, such as poor blood glucose levels, nephropathy, worsening retinopathy, hypertension or preeclampsia, or limited or excessive fetal growth. Waiting for labor to start on its own is reasonable if blood glucose levels are well-controlled and the mother and fetus are without problems. However, extending pregnancy beyond 40 to 41 weeks of gestation is generally not recommended If the fetus appears to be very large (based upon ultrasound measurements), a woman and her obstetrician should consider cesarean delivery to avoid possible trauma from shoulder dystocia. The infant of the diabetic mother is at risk for several problems in the newborn period, such as low blood glucose levels (less than 30 mg/dL [1.7 mmol/L]), jaundice, too many red blood cells (polycythemia), low calcium level, and heart problems. These problems are more common when the mother's blood glucose levels have been elevated during the pregnancy. Most of these problems resolve within a few hours or days of delivery. Infants of diabetic mothers are often evaluated in a special care nursery to monitor for these potential problems. Postpartum (after delivery) care for a woman with diabetes is similar to that for women without diabetes. However, insulin requirements are highly variable in the immediate postpartum period; some women require little or no insulin. Insulin requirements usually return to near-prepregnancy levels within 48 hours. Breastfeeding is strongly encouraged, and benefits both the infant and the mother. Insulin requirements may be lower while breastfeeding, and frequent blood glucose monitoring is important to prevent severe hypoglycemia. Approximately 400 additional calories are required each day while breastfeeding. Breastfeeding for longer than three months can aid in maternal weight loss and provides significant short and long-term benefits to the infant.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov/)
American Diabetes Association (ADA)
(800)-DIABETES (800-342-2383)
(www.diabetes.org)
The Endocrine Society
(www.endo-society.org)
The Hormone Foundation
(www.hormone.org/public/diabetes.cfm, available in English and Spanish)
[1-4]
Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Diabetes mellitus in pregnancy. Obstet Gynecol Clin North Am Dec 2004.
2. Bernasko, J. Contemporary management of type 1 diabetes mellitus in pregnancy. Obstet Gynecol Surv 2004; 59:628.
3. Preconception care of women with diabetes. Diabetes Care 2004; 27 Suppl 1:S76.
4. Gabbe, SG, Graves, CR. Management of diabetes mellitus complicating pregnancy. Obstet Gynecol 2003; 102:857.
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