You frequently feel out of energy or shaky after a meal. You think you might have low blood sugar, or hypoglycemia. However, when you or your doctor checks your blood sugar, it’s in the healthy range. If this sounds familiar to you, you might have idiopathic postprandial syndrome (IPS).

People with IPS have the symptoms of hypoglycemia two to four hours after a meal but don’t have low blood glucose. This usually occurs after eating a high-carbohydrate meal. Other names for IPS are:

  • carbohydrate intolerance
  • adrenergic postprandial syndrome
  • idiopathic reactive hypoglycemia

Learn more: The Effects of Low Blood Sugar on the Body »

IPS differs from hypoglycemia in a few ways:

  • Blood sugar levels in people with hypoglycemia are below 70 milligrams per deciliter (mg/dL). People who have IPS may have blood sugar levels in the normal range, which is 70 to 120 mg/dL.
  • Hypoglycemia can lead to long-term damage of the nervous system and kidneys. IPS can disrupt your daily living, but it doesn’t lead to long-term damage.
  • IPS is more common than hypoglycemia. Most people who experience fatigue or shakiness after a meal have IPS rather than clinical hypoglycemia.

The symptoms of IPS are similar to hypoglycemia, but they’re usually less severe. The following IPS symptoms can occur after a meal:

  • shakiness
  • nervousness
  • anxiety
  • sweating
  • chills
  • clamminess
  • irritability
  • impatience
  • confusion, including delirium
  • a rapid heart rate
  • lightheadedness
  • dizziness
  • hunger
  • nausea
  • sleepiness
  • blurred or impaired vision
  • tingling or numbness in the lips or tongue
  • headaches
  • weakness
  • fatigue
  • anger
  • stubbornness
  • sadness
  • a lack of coordination
  • nightmares or crying out during sleep
  • seizures
  • unconsciousness

The symptoms of IPS don’t usually progress to seizures, coma, or brain damage, but these can occur with severe hypoglycemia. Additionally, people who have hypoglycemia may not have any notable symptoms in their daily lives.

Researchers don’t know what causes IPS. It may occur due to a release of the hormone epinephrine, also known as adrenaline, into the bloodstream. This leads to the symptoms associated with hypoglycemia.

People who have IPS release high amounts of epinephrine when their blood glucose levels are normal. The following might also contribute to the syndrome, especially in people without diabetes:

  • a blood glucose level that’s in the lower levels of the healthy range
  • eating foods with a high glycemic index
  • a higher blood glucose level that rapidly drops but stays within the healthy range
  • a deficiency in glucagon, which is a hormone that increases blood sugar
  • an excess production of insulin from the pancreas
  • low levels of the hormone cortisol
  • illnesses that affect the renal system, which includes the kidneys
  • a high consumption of alcohol

People with hormonal imbalances may be more likely to experience IPS. Additionally, people who’ve had stomach surgery may also have an increased risk. This is because stomach surgery can affect your stomach enzymes. This can disrupt the production of insulin and the absorption of nutrients. People who’ve suddenly lost a lot of weight may also be at risk for IPS.

Most people who have IPS don’t need medical treatment. Your doctor may recommend that you modify your diet to decrease your chances of low blood sugar.

The following dietary changes may help:

  • Eat high-fiber foods, such as green vegetables, fruits, whole grains, and legumes.
  • Consume lean proteins from meat and nonmeat sources, such as chicken breast and lentils.
  • Eat several small meals throughout the day with no more than three hours between meals.
  • Avoid large meals.
  • Eat foods that are high in healthy fats, such as avocados and olive oil.
  • Avoid or limit foods and beverages that are high in sugars and refined carbohydrates.
  • If you’re drinking alcohol, avoid having soft drinks, such as soda, as mixers.
  • Limit your intake of starchy foods, such as potatoes, white rice, and corn.

If these dietary changes don’t provide relief, your doctor might prescribe certain medications. Drugs known as alpha-glucosidase inhibitors might be particularly helpful. Doctors typically use them to treat type 2 diabetes.

If you frequently lack energy after eating but have healthy blood sugar levels, talk with your doctor about your symptoms and medical history. Work with your doctor to identify a potential cause. If you have IPS, making changes to your diet may help.


Does IPS increase my risk for developing diabetes?


At this time, there’s no conclusive evidence that IPS increases the risk for diabetes.

Deborah Weatherspoon, Ph.D, MSN, RN, CRNAAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.