What is hypoglycemia?

Hypoglycemia is low blood sugar. It occurs when the level of sugar, or glucose, in the blood drops too low to give the body energy. The medical condition of low blood sugar occurs when all 3 of the following are present:

• Blood sugar is low.
• Low blood sugar is causing symptoms.
• The symptoms go away when blood sugar returns to normal.

Fasting blood sugar levels are measured in mg/dL. A fasting blood sugar level of:

• 70 to 99 mg/dL is normal.
• 50 to 69 mg/dL is mildly low.
• Less than 50 mg/dL is very low.

The bloodstream carries glucose-a type of sugar produced from the digestion of carbohydrates and other foods-to provide energy to cells throughout the body. Unused glucose is stored mainly in the liver as glycogen. Insulin, glucagon, and other hormone levels rise and fall to keep blood sugar in a normal range. Too little or too much of these hormones can cause blood sugar levels to fall too low (hypoglycemia)

Normally, blood glucose levels increase slightly after you eat a meal. When blood sugar rises, cells in the pancreas release insulin, causing the body to absorb glucose from the blood, which lowers the blood sugar level to normal. When blood sugar drops too low, the level of insulin declines and other cells in the pancreas release glucagon, which causes the liver to turn stored glycogen back into glucose and release it into the blood. Low blood sugar also triggers the release of hormones by the pituitary and adrenal glands. These hormones also help bring sugar back to normal.

Hypoglycemia is not a disease but a condition that results from a variety of causes.

What causes hypoglycemia?

Hypoglycemia is most commonly a complication of diabetes treatment, but it is otherwise rare.

Hypoglycemia may also result from:

• Medicines, such as monoamine oxidase inhibitors (MAOIs), quinine sulfate, and salicylates (including aspirin).
• Drinking too much alcohol.
• Diseases that affect the pancreas, liver, kidneys, adrenal glands, or other organs.
• Inherited problems with metabolism.
• Rapid stomach emptying after a meal. This may happen after stomach surgery.

What are the symptoms?

The symptoms can vary depending on how low the blood sugar level drops.

• Mild hypoglycemia can cause nausea, a jittery or nervous feeling, cold and clammy skin, sweating, hunger, and a rapid heartbeat.
• Moderate hypoglycemia often makes you feel irritable, anxious, or confused. You may have blurred vision, feel unsteady, and have difficulty walking.
• Severe hypoglycemia can lead to loss of consciousness, seizures, and coma-and it may be fatal.

Some medicines may mask symptoms of low blood sugar, including beta-blockers, which are often used to treat heart conditions and high blood pressure.

How is hypoglycemia diagnosed?

Doctors diagnose hypoglycemia using a medical history, physical examination, and tests to check blood sugar levels. Generally, you are diagnosed with the condition if a blood test shows you have low blood sugar and you have symptoms of hypoglycemia that go away after you eat carbohydrate such as sugar.