What is Reactive Hypoglycemia? Causes, Symptoms, Treatment

Posted September 25, 2020 by Clint Kelly - See Editorial Guidelines

Have you felt your blood sugar drop after eating and wondered why? This could be reactive hypoglycemia, sometimes called postprandial hypoglycemia.

To get a better understanding of this condition, we’ll cover the causes, symptoms, and treatment of reactive hypoglycemia in this article. First, here is a basic explanation to help get us started.

What is Reactive Hypoglycemia? Reactive hypoglycemia is when your blood sugar levels drop low within four hours after eating. This condition is considered a non-diabetic hypoglycemia. Meaning, those without diabetes can experience low blood glucose levels. The exact cause of reactive hypoglycemia is not fully known, but there are underlying conditions that could be associated with it.

Now that you have a basic understanding let’s get into more of the specifics.

What is Reactive Hypoglycemia?

What is Reactive Hypoglycemia

Low blood sugar is defined as any blood glucose level below 70 mg/dL.

Reactive hypoglycemia is characterized by a person having low blood sugar levels within four hours after eating. It is also referred to as postprandial hypoglycemia.

Reactive hypoglycemia after eating can occur in those that have diabetes if they have injected too much insulin or gave their insulin too soon. If you are on insulin or use other glucose-lowering medications, then talk to your doctor about adjusting your dose. However, most people that struggle with this condition do not have diabetes, and the cause is not fully known.

Reactive hypoglycemia is one of two main types of hypoglycemia that can affect non-diabetics. The other is fasting hypoglycemia, which can be related to a serious underlying condition.

Medical treatment is typically not needed for postprandial hypoglycemia. However, severe hypoglycemia can lead to unconsciousness and seizures. In those that have diabetes, it can be life-threatening.

Causes of Reactive Hypoglycemia

Though it is not very clear what causes reactive hypoglycemia, many believe that it has to do with the foods consumed. A high carbohydrate meal could cause your body to make too much insulin, causing a dip in blood sugar after eating. Your body may continue to release insulin even after you have fully digested the meal.

Other possible causes of reactive hypoglycemia may include alcohol consumption, medications you are taking, surgical procedures, metabolic disorders, and tumors.

Insulinoma is a rare but benign tumor of the pancreas. This type of tumor can cause an excess of insulin to be secreted, leading to low blood sugar levels.

Patients that have had a gastric bypass surgery may have an increased risk of reactive hypoglycemia. This is due to the food being rapidly emptied into the small intestines, known as “dumping” syndrome. The pancreas secretes an excessive amount of insulin in response to this, which then leads to a drop in blood sugar.

A certain enzyme deficiency may also cause reactive hypoglycemia. An enzyme deficiency can impact the body’s ability to break down food.

Related: What Can Cause Low Blood Sugar?

Signs and Symptoms

The most common signs and symptoms of reactive hypoglycemia include:

  • Nausea
  • Shaking and tremors
  • Hunger
  • Rapid heart rate
  • Anxiety
  • Tingling of the lips and tongue
  • Sweating
  • Headache
  • Fatigue and weakness
  • Trouble concentrating
  • Dizziness
  • Irritability and restlessness

Some cases of reactive hypoglycemia may become severe. Severe symptoms may include:

  • Confusion
  • Changes in your behavior
  • Slurring speech
  • Changes in vision
  • Unconsciousness
  • Seizures

How is Reactive Hypoglycemia Diagnosed?

What is Reactive Hypoglycemia

The easiest way to diagnose if someone has reactive hypoglycemia is to perform a blood glucose test while they are having symptoms. The individual should then be observed to determine if their symptoms subside once their blood sugar levels go back into normal range. This doesn’t really help to get to the root of the problem, though.

Your doctor may order you to do a mixed meal tolerance test. This is a test that helps determine how much insulin your body is making in response to consuming a beverage containing carbs, proteins, and fats. Blood glucose levels will be checked before drinking the beverage, and every 30 minutes after. This will give doctors a better understanding of whether your pancreas is under-producing or over-producing insulin.

Your doctor may also order blood work to be done. Labs can determine if there are other areas of your health to be concerned about.

Related: How To Properly Check Blood Sugar

Treating and Preventing Reactive Hypoglycemia

Treating reactive hypoglycemia will depend on what is causing the problem. If you have an underlying medical condition that is leading to low blood sugar after you eat, then that medical condition must be treated first. For example, if you have an insulinoma, then having surgery to remove the tumor can stop reactive hypoglycemia from occurring.

If the exact cause of reactive hypoglycemia has not been determined, then certain adjustments to your lifestyle can prevent the condition.

Avoid consuming large meals that have high amounts of carbohydrates. This means limiting your intake of simple carbs and sugary foods. Examples of these foods include white bread, sugary drinks, cereals, and pastry items.

Eating smaller meals more often throughout the day can help prevent an insulin dump form the pancreas, limiting your risk of reactive hypoglycemia. Healthy eating, which consists of a balanced diet including proteins, fibers, fruits, and vegetables will prove to be beneficial.

Avoid binge drinking and consuming large amounts of alcohol in short periods. Alcohol consumption can be particularly dangerous for those with diabetes.

Regular exercise can trigger the muscles to pull glucose directly from the bloodstream for energy. It can also improve your insulin sensitivity. Therefore, exercising regularly prevents the need for large amounts of insulin to be secreted by the pancreas, reducing the risk of hypoglycemia after eating.

Related: What to Do for Low Blood Sugar

Can Reactive Hypoglycemia Lead to Diabetes?

Reactive hypoglycemia is not normal and could be a sign of prediabetes, which can lead to insulin resistance. If you have continuously had symptoms of this condition, then you should see your doctor. Nearly one in three Americans have prediabetes. Taking action and making adjustments to your lifestyle right away can prevent prediabetes from turning into type 2 diabetes.


If you continue to struggle with hypoglycemic events, then you may need glucagon in case of an emergency. We hope that this has given you a better understanding of reactive hypoglycemia and what you can do about it.

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What is reactive hypoglycemia?

Reactive hypoglycemia, also called postprandial hypoglycemia, is when one’s blood sugar drops below 70 mg/dL within 4 hours after a meal.

Is reactive hypoglycemia a sign of diabetes?

Reactive hypoglycemia could potentially be a sign of diabetes or prediabetes, but there could also be other causes other than diabetes. Therefore, patients should see their doctor if they are experiencing this type of low blood sugar to determine if this is a sign of an underlying condition.

What triggers reactive hypoglycemia?

The cause of reactive hypoglycemia could be attributed to consuming a meal high in carbohydrates, which could trigger your pancreas to overproduce insulin.