Health Encyclopedia

Hypoglycemia

Definition

Hypoglycemia is a condition that occurs when your blood sugar (glucose) is too low.

Alternative Names

Insulin shock; Low blood sugar

Causes, incidence, and risk factors

Hypoglycemia occurs when:

Your body's sugar (glucose) is used up too quickly
Glucose is released into the bloodstream too slowly
Too much insulin is released into the bloodstream

Insulin is a hormone that reduces blood sugar. It is produced by the pancreas in response to increased glucose levels in the blood.

Hypoglycemia is relatively common in persons with diabetes. It occurs when:

You take too much insulin or diabetes medicine
You don't eat enough food
You suddenly increase your exercise without increasing the amount of food you eat

Relative hypoglycemia is a fairly common condition in which a newborn's blood sugar is low. Babies born to mothers with diabetes may have severe hypoglycemia.

Idiopathic hypoglycemia is hypoglycemia that occurs without a known cause. People with this type of hypoglycemia do not have diabetes.

Hypoglycemia may also be caused by:

Ingestion of alcohol
Insulin-secreting tumor of the pancreas
Liver disease

Symptoms

Cold sweats
Confusion
Convulsions
Coma
Double vision or blurry vision
Fatigue
General discomfort, uneasiness, or ill feeling (malaise)
Headache
Hunger
Irritability (possible aggression)
Nervousness
Rapid heart rate
Trembling

Other symptoms that may be associated with this disease:

Decreased alertness
Different size pupils
Dizziness
Excessive sweating
Fainting
Hallucinations
Memory loss
Muscle pain
Paleness
Pounding heartbeat (heartbeat sensations)
Sleeping difficulty

Signs and tests

Home monitoring of blood sugar will show readings lower than 50 mg/dL.

Serum glucose test will be low.

Treatment

Treatment depends on the cause.

In people with diabetes who take medication that lowers blood sugar, a snack or drink containing sugar will raise the blood glucose level. Try to drink no more than 4 ounces of juice or sugar soda. You should see an immediate improvement in symptoms. If you do not, check blood sugar and repeat after 15 minutes. Overtreatment of low blood sugar can cause problems with high blood sugar in people with diabetes.

Persons with severe hypoglycemia are treated with glucose injections or the hormone glucagon. Immediate treatment is needed to prevent serious complications or death.

Your doctor may tell you to change your diet so that you get more even amounts of glucose into your body throughout the day. This may prevent further episodes of low blood sugar. You may be told to eat small, frequent meals with complex carbohydrates, fiber, and fat and to avoid simple sugars, alcohol, and fruit juice.

You should also eat meals at regular intervals, and balance extra exercise with extra food.

If hypoglycemia is caused by an insulinoma (insulin-secreting tumor), surgery to remove the tumor is the best treatment.

Complications

Untreated, hypoglycemia from too much insulin can lead to loss of consciousness and coma. Severe hypoglycemia is a medical emergency that may result in seizures and permanent damage to the nervous system if not treated. Severe hypoglycemia that results in unconsciousness is also called insulin shock.

Learn to recognize the early warning signs of hypoglycemia and treat yourself quickly and appropriately.

Calling your health care provider

Go to the emergency room immediately or call a local emergency number (such as 911) if early signs of hypoglycemia do not improve after you've eaten a snack containing sugar.

Get immediate medical help if a person with diabetes or a history of hypoglycemia loses alertness or if you can't wake them up.

Prevention

If you have diabetes, make sure you follow your doctor's advice regarding diet, medications, and exercise.

If you have a history of hypoglycemia, you should keep a snack or drink containing sugar available at all times to take as soon as symptoms appear. If symptoms do not improve in 15 minutes, eat more food. A glucagon kit is available for those who have episodes of hypoglycemia that don't respond well to other types of treatment.

References

Cryer PE, Davis SN, Shamoon H. Hypoglycemia in diabetes. Diabetes Care. 2003; 26(6): 1902-1912.

Cryer PE. Glucose Homeostasis and Hypoglycemia. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa:Saunders Elsevier; 2008:chap 33.

Review Date:5/20/2009
Reviewed By:Reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Also reviewed by Deborah Wexler, MD, Assistant Professor of Medicine, Harvard Medical School, Endocrinologist, Massachusetts General Hospital.

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