Hypoglycemia

(Low Blood Glucose; Low Blood Sugar)

by Rick Alan

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 50-60 mg/dl (milligrams per deciliter), 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.

Glucose in Blood

© 2009 Nucleus Medical Media, Inc.

Causes

Medication for diabetes is the most common cause particularly when combined with the following factors:

• Taking too much blood sugar-lowering medication
• 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:

• Drinking too much alcohol (especially binge drinking coupled with not eating)
• Prolonged fasting
• Early pregnancy
• Long periods of strenuous exercise
• Certain medications may increase the risk of hypoglycemia (people on beta blockers who exercise, aspirin in children)
• Certain pituitary or adrenal gland conditions
• Certain liver conditions
• Certain types of stomach surgery
• Certain autoimmune conditions
• Hereditary enzyme or hormone deficiencies
• A reaction to certain foods (rarely, eating unripe ackee fruit from Jamaica)
• Pancreatic tumors
• Tumors that produce an insulin-like hormone
• Any severe or protracted illness, such as:
  • Heart or kidney failure
  • Metastatic cancer
  • Malnutrition
  • Severe infection

Risk Factors

Factors that can increase your risk for hypoglycemia include:

• Diabetes
• Drinking too much alcohol
• Fasting, particularly in combination with strenuous exercise
• Family history of hypoglycemia

Symptoms

Symptoms may come on slowly or suddenly.

Symptoms include:

• Sweating
• Nervousness
• Feeling faint
• Heart palpitations
• Hunger
• Headache

As hypoglycemia worsens symptoms may include:

• Fatigue
• Dizziness
• Weakness
• Inappropriate behavior or severe confusion
• 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 this is not possible, you may have a glucose tolerance test. This is a series of blood tests after taking glucose by mouth.

Other, less routine tests include:

• Laboratory tests for antibodies to insulin
• Imaging tests to check for a tumor, such as:
  • MRI scan —a test that uses radio waves and magnetic fields to make pictures of structures inside the body
  • CT scan —a type of x-ray that uses a computer to make pictures of structures inside the body
  • Ultrasound—a test that uses sound waves to make pictures of structures inside the body

Treatment

Treatments include:

Prevention

Measures that can help prevent hypoglycemia include:

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

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

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

Canadian Health Network
http://www.canadian-health-network.ca/

REFERENCES:

Beers MH. The Merck Manual of Medical Information . 2nd ed. London, England: Simon and Schuster, Inc; 2003.

Berkow R. The Merck Manual of Medical Information . New York, NY: Pocket; 2000.

Hypoglycemia. American Diabetes Association website. Available at: http://www.diabete... . Accessed July 1, 2009.

Hypoglycemia. National Institute of Diabetes & Digestive & Kidney Diseases website. Available at: http://www2.niddk.nih.gov/ . Published October 2008. Accessed July 1, 2009.

Last reviewed September 2009 by Igor Puzanov, MD
Last Updated: 9/30/09