Reactive hypoglycemia: What causes it?

Most hypoglycemia, or low blood sugar, occurs while fasting. But reactive hypoglycemia is low blood sugar that occurs after a meal — usually one to three hours after eating. Reactive hypoglycemia can occur in people who do not have diabetes. The cause of most cases of reactive hypoglycemia isn't clear.

Some researchers suggest that certain people may be overly sensitive to the normal release of the hormone epinephrine, which causes many of the symptoms of hypoglycemia. Others believe that deficiencies in glucagon — a hormone that normally protects against low blood sugar — may cause reactive hypoglycemia.

Less commonly, reactive hypoglycemia results from excessive production of insulin by the pancreas (hyperinsulinemia) due to a tumor (insulinoma) or high numbers of insulin-producing cells (nesidioblastosis). Reactive hypoglycemia may also occur after stomach surgery or due to certain enzyme deficiencies, which may interfere with the balance between nutrient absorption and insulin secretion.

Symptoms of hypoglycemia include:

• Hunger
• Nervousness
• Perspiration
• Shakiness
• Dizziness
• Sleepiness
• Confusion
• Weakness
• Anxiety

Reactive hypoglycemia is often difficult to diagnose. Some people who have symptoms that are similar to reactive hypoglycemia may not actually have reactive hypoglycemia. Reactive hypoglycemia typically is not associated with diabetes.

Medical evaluation of reactive hypoglycemia initially focuses on confirming that symptoms are caused by low blood sugar and symptoms resolve once blood sugar has returned to normal. Further evaluation of reactive hypoglycemia depends on the severity of signs and symptoms.

Reactive hypoglycemia usually doesn't require treatment. When needed, treatment may include dietary changes such as:

• Eating several small meals and snacks throughout the day — no more than three hours apart
• Avoiding or limiting high-sugar foods, especially on an empty stomach