Type 2 Diabetes Hypoglycemia What Is Reactive Hypoglycemia? By Debra Manzella, RN linkedin Debra Manzella, MS, RN, is a corporate clinical educator at Catholic Health System in New York with extensive experience in diabetes care. Learn about our editorial process Debra Manzella, RN Medically reviewed by Medically reviewed by Ana Maria Kausel, MD on September 01, 2020 facebook twitter Ana Maria Kausel, MD, is double board-certified in internal medicine and endocrinology/diabetes and metabolism. She works in private practice and is affiliated with Mount Sinai St. Luke's/Mount Sinai West. Learn about our Medical Review Board Ana Maria Kausel, MD Updated on September 11, 2020 Print Reactive hypoglycemia, also called postprandial hypoglycemia, is a drop in blood glucose (blood sugar) levels. This typically happens within four hours after eating and is not related to diabetes. Usually, a definitive cause of reactive hypoglycemia cannot be determined, although there are a handful of medical diseases and conditions known to be associated with it. In those cases, treating the underlying issue will put an end to post-meal low blood sugar. Otherwise, managing reactive hypoglycemia starts with recognizing the symptoms, which can range from mild (shaking, rapid heart rate, anxiety, hunger) to serious (confusion, vision difficulties, behavioral changes, seizures, or even loss of consciousness). Alex Dos Diaz / Verywell Symptoms Reactive hypoglycemia can cause symptoms that range from common ones that are mild and unsettling to less frequent symptoms that can become serious and even life-threatening if the condition isn't treated. Hypoglycemia: Signs, Symptoms, and Complications Common Symptoms Shaking or tremorsHungerRapid heartbeatAnxiety or panicTingling near the mouthSweatingA headacheFatigueInability to concentrateDilated pupilsIrritabilityRestlessnessNauseaDizzinessWeaknessLoss of muscle control Severe Symptoms ConfusionChanges in behaviorSlurred speechClumsy movementsBlurry or double visionSeizuresLoss of consciousness Diagnosis Reactive hypoglycemia can be diagnosed by measuring the amount of glucose in a person's blood while they're having symptoms that develop after eating as well as by observing whether or not those symptoms resolve once glucose levels return to normal. If testing reveals a postprandial blood glucose level below 70 milligrams per deciliter (mg/dL), a doctor may order a mixed meal tolerance test (MMTT). For this test, a person downs a beverage that contains protein, carbohydrates, and fat such as Ensure or Boost. Before ingesting the beverage and every 30 minutes for five hours, his or her blood will be tested to check levels of glucose as well as insulin, proinsulin (a precursor to insulin), and a substance produced in the pancreas along with insulin. How Hypoglycemia Is Diagnosed Causes For the majority of people who experience reactive hypoglycemia, there's no apparent or diagnosable reason for the characteristic blood sugar dips. However, there are a few known potential causes: Insulinoma, a rare, usually benign tumor made up of abnormal beta cells—the cells that produce insulin needed to maintain normal blood sugarExcessive intake of insulin by someone who has diabetesGastric bypass surgery, which may cause food to pass so quickly through the digestive system that not all of it is digested and therefore is absorbed as glucose into the bloodstreamHernia surgeryCertain inherited metabolic disorders—specifically known as endogenous hyperinsulinism linked to non-insulinoma pancreatogenic hypoglycemia syndrome (NIPHS) or very rarely, inherited fructose intoleranceEnzyme deficiencies that interfere with the body's ability to break down food Too much insulin intake can cause lower levels of glucose in the blood. Treatment If it's determined that an underlying medical issue is causing reactive hypoglycemia, treating that disease or condition should put an end to post-meal dips in blood glucose. In the case of an insulinoma, surgical removal of the tumor should put an end to post-meal hypoglycemia. For all other cases, there are two distinct aspects of treating reactive hypoglycemia. The first is knowing what to do to alleviate symptoms when they occur. The second is making lifestyle changes and taking other steps to prevent blood sugar drops after meals to occur in the first place. Treating Hypoglycemia With Fast-acting Carbs Dealing With an Episode The symptoms of reactive hypoglycemia can be mitigated by taking certain steps to return blood glucose levels to normal: First, follow the "15-15 Rule," which involves eating 15 grams of fast-acting carbohydrates and checking your blood sugar after 15 minutes. If it’s still below 70 mg/dL, have another serving. Fast-acting Carbs Banana (half)Corn syrup (1 tablespoon)Fruit juice (usually 1/2 to 3/4 cup, or 4–6 ounces)Glucose gel (one small tube is usually 15 g)Glucose tablets (3–4)Honey (1 tablespoon)LifeSavers (6–8)Orange juice (1/2 cup, or 4 ounces)Raisins (2 tablespoons)Nonfat milk (1 cup, or 8 ounces)Soda with sugar (1/2 cup, or 4 ounces)Sugar (1 tablespoon or 5 small sugar cubes)Syrup (1 tablespoon)Hard candies, jelly beans, and gumdrops (check the label for how many equal 15 grams of carbohydrate) Once your symptoms have resolved, eat a small snack or meal to prevent your blood sugar from spiking and dropping again. Some good options are: Glucose tablets (see instructions)Gel tube (see instructions)4 ounces (1/2 cup) of juice or regular soda (not diet)1 tablespoon of sugar, honey, or corn syrupHard candies, jellybeans, or gumdrops—see food label for how many to consume Guide to Low-carb Snacks Prevention The cause of most cases of reactive postprandial hypoglycemia cannot be determined. Even so, certain dietary and lifestyle changes are known to help prevent it: Limit foods that have a high glycemic index, such as sugary ones and processed simple carbs like white bread and pasta—especially on an empty stomach. For example, eating a doughnut first thing in the morning can trigger a hypoglycemic episode.Eat small, frequent meals and snacks that include fiber and protein. Don't go longer than three hours without eating.If you drink alcohol, always eat while you imbibe. Don't use sugary soft drinks as mixers.Eat a balanced and varied diet that includes protein, whole-grain carbs, vegetables, fruits, dairy foods, and lots of fiber.Exercise regularly: Physical activity increases the amount of glucose taken up by the blood which in turn prevents the release of excessive insulin. Exercise for Managing Diabetes A Word From Verywell If you experience the symptoms of low blood sugar levels after you eat, see your doctor. Some symptoms can be similar to those of other conditions, such as heart disease, so you'll want to be certain a potentially serious medical problem isn't responsible for your post-meal dips in glucose. Once it's clear you're experiencing reactive hypoglycemia, even if your doctor can't find a specific reason it should be a relief to know that there are simple measures you can take to handle, and prevent, episodes from occurring. Was this page helpful? Thanks for your feedback! We know healthy eating is key to help manage diabetes, but that doesn't make it easy. Our free nutrition guide is here to help. Sign up and receive your free copy! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. National Institute of Diabetes and Digestive and Kidney Diseases. Low blood sugar (hypoglycemia). Updated August, 2016. Stuart K, Field A, Raju J, Ramachandran S. Postprandial reactive hypoglycaemia: Varying presentation patterns on extended glucose tolerance tests and possible therapeutic approaches. Case Rep Med. 2013;2013:273957. doi:10.1155/2013/273957 Martens P, Tits J. Approach to the patient with spontaneous hypoglycemia. Eur J Intern Med. 2014 Jun;25(5):415-21. doi: 10.1016/j.ejim.2014.02.011 Galati SJ, Rayfield EJ. Approach to the patient with postprandial hypoglycemia. Endocr Pract. 2014 Apr;20(4):331-40. doi:10.4158/EP13132.RA Salehi M, Vella A, McLaughlin T, Patti ME. Hypoglycemia after gastric bypass surgery: Current concepts and controversies. J Clin Endocrinol Metab. 2018;103(8):2815–2826. doi:10.1210/jc.2018-00528 Douillard C, Mention K, Dobbelaere D, Wemeau JL, Saudubray JM, Vantyghem MC. Hypoglycaemia related to inherited metabolic diseases in adults. Orphanet J Rare Dis. 2012;7:26. Published 2012 May 15. doi:10.1186/1750-1172-7-26 Brutsaert EF. Hypoglycemia. Merck Manual Professional Version. Updated January, 2019. American Diabetes Association. Hypoglycemia (low blood sugar). Additional Reading Haider A, Burks JK, Cheema H, et al. Postprandial hypoglycemia: Complication of peptic ulcer surgery. Am J Med. 2017 Dec;130(12):e527-e529. doi:10.1016/j.amjmed.2017.06.010 Service FJ, Vella A. Hypoglycemia in adults without diabetes mellitus: Diagnostic approach. UpToDate. Updated September 19, 2018. Service FJ, Vella A. Postprandial (reactive) hypoglycemia. UpToDate. Updated June 11, 2018