What Is Reactive Hypoglycemia?

Medically Reviewed by Michael Dansinger, MD on December 08, 2021
3 min read

All day long, your blood sugar levels go up and down. If the sugar -- or glucose -- levels in your blood are too low, you can sometimes get a condition called hypoglycemia.

Hypoglycemia mainly affects people with diabetes, but there are two types that can happen to anyone:

  • Fasting hypoglycemia usually results from an underlying disease.
  • Reactive hypoglycemia often happens not long after you eat. You may hear it called postprandial hypoglycemia.

The symptoms of reactive hypoglycemia generally start within 4 hours after a meal. They can include:

The answer isn’t always clear. It’s likely the result of your body making too much insulin after a large, carb-heavy meal. Scientists aren’t sure why, but sometimes your body continues to release extra insulin even after you’ve digested your meal. This added insulin makes your blood glucose level drop below normal.

Reactive hypoglycemia can also result from tumors, alcohol, surgeries -- like gastric bypass or ulcer treatment -- and possibly some metabolic diseases. It’s more common if you’re overweight.

Talk to your doctor if you think you’ve had an episode of hypoglycemia. They’ll ask about your symptoms, medical history, and if other people in your family have had diabetes.

The doctor may check your blood sugar while you’re having symptoms and compare it to a reading taken after the symptoms go away.

You might need a mixed-meal tolerance test, or MMTT. You’ll get a syrupy drink to raise your blood sugar and cause your body to make more insulin. The doctor will check your blood sugar several times over the next 5 hours to see if your levels drop too low.

Treatment depends on what’s causing your hypoglycemia.

If you have diabetes, check your blood sugar levels. For people with diabetes, a reading below 70 mg/dL means you’re hypoglycemic.

Eat 15 grams of carbohydrates, then check your blood sugar after 15 minutes. If it’s still below 70 mg/dL, have another serving. Repeat until your blood sugar is at least 70 mg/dL. Talk to your doctor to see if you need a new treatment plan.

If you know the specific cause of your hypoglycemia, your doctor will treat that cause. For example, if a medicine or tumor is triggering your hypoglycemia, you may need a new drug or possibly surgery.

Most people don’t need medical treatment to manage reactive hypoglycemia. Instead, there are changes you can make at home. Often changing your diet can help your symptoms.

Here are some things you can try:

  • Eat small meals and snacks about every 3 hours.
  • Choose a variety of foods including protein (meat and nonmeat), fruits and vegetables, dairy products, and whole grains.
  • Avoid foods that are high in sugar and highly refined carbs, like white bread.
  • If you drink, eat food with your alcohol.
  • Get regular exercise.