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Hypoglycemia

(Low Blood Glucose; Low Blood Sugar)

Definition

Glucose is a type of sugar. It is your body's main source of energy. Hypoglycemia is a condition where the level of glucose in your blood becomes low enough to cause symptoms. For most people, this level is around 50 milligrams per deciliter (mg/dl), though anything below 70 mg/dl is considered below normal. When blood glucose drops too low, your body does not have enough energy to function properly.

Causes

Medicine for diabetes is the most common cause particularly when combined with the following factors:
  • Taking too much blood sugar-lowering medicine
  • Delaying or missing meals, or eating too little at meals
  • Too much or too strenuous exercise
Reactive hypoglycemia may also occur in people without diabetes. It is now thought to be quite rare.
Other causes of hypoglycemia include:
  • Alcohol abuse (especially binge drinking coupled with not eating)
  • Starvation
  • Early pregnancy
  • Certain pituitary or adrenal gland conditions
  • Certain liver conditions
  • Kidney disease
  • Certain types of stomach surgery
  • Tumor that makes insulin
  • Hereditary enzyme or hormone deficiencies
  • Severe illness or infection

Risk Factors

Factors that may increase the risk of hypoglycemia include:
  • Having diabetes
  • Taking medicines that lower blood sugar levels
  • Drinking too much alcohol
  • Fasting (particularly in combination with strenuous exercise)

Symptoms

Symptoms may come on slowly or suddenly and may include:
  • Sweating
  • Nervousness
  • Lightheadedness
  • Heart palpitations
  • Hunger
  • Headache
  • Tingling feeling around the mouth
As hypoglycemia worsens, symptoms may include:
  • Fatigue
  • Dizziness
  • Weakness
  • Inappropriate behavior or severe confusion
  • Poor control of movements
  • Seizure
  • Loss of consciousness

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done.
If hypoglycemia is suspected, your doctor will try to document your low blood sugar. Your blood glucose levels will be measured while you are having symptoms.
If you do not have diabetes and you do not take medicines that lower your blood sugar levels, the doctor may do other tests to see if and why you are having low blood sugar levels. These tests may include checking your blood levels after periods of not eating.

Treatment

Treatments include:

Sugar

Symptoms of low blood sugar can be relieved quickly by:
  • Eating sugar in a rapidly absorbable form, such as:
    • Fruit juice
    • Sugared soft drink
    • Table sugar in water
    • Honey or corn syrup
  • Taking glucose tablets
  • IV glucose (in severe cases)

Medication

Some people who have prolonged or severe hypoglycemia take glucagon. Glucagon is an injectable hormone. It raises blood sugar levels.

Surgery

Some cases of hypoglycemia are caused by a tumor. In this case, the tumor may need to be removed.

Prevention

Measures that can help prevent hypoglycemia include:
  • For people with diabetes
    • Monitor your medicine. Take it as prescribed.
    • Follow the diet and exercise plans given by your doctor.
    • Avoid drinking alcohol in excess.
  • Non-diabetic people prone to hypoglycemia
    • Avoid drinking too much alcohol.
    • Eat frequent, small meals.
    • Eat enough food before exercising.
If you are prone to severe hypoglycemia:
  • Wear a medical alert bracelet or other medical alert identification.
  • Learn to recognize symptoms and take quick corrective measures.

RESOURCES

American Diabetes Association http://www.diabetes.org/

Hypoglycemia Support Foundation http://www.hypoglycemia.org/

CANADIAN RESOURCES

Canadian Diabetes Association http://www.diabetes.ca/

Health Canada http://www.hc-sc.gc.ca/

References

Hypoglycemia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/. Updated February 3, 2012. Accessed July 31, 2012.

Hypoglycemia. National Institute of Diabetes & Digestive & Kidney Diseases website. Available at: http://diabetes.niddk.nih.gov/dm/pubs/hypoglycemia/index.aspx. Published October 2008. Accessed July 26, 2012.

Hypoglycemia (low blood glucose). American Diabetes Association website. Available at: http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hypoglycemia-low-blood.html. Accessed July 26, 2012.

Kasper D, Harrison T. Harrison's Principles of Internal Medicine. New York: McGraw-Hill; 2005.

Revision Information

  • Reviewer: Brian Randall
  • Review Date: 09/2012 -
  • Update Date: 00/91/2012 -

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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