Hypoglycemia after Bariatric Surgery

Mary-Elizabeth Patti MD FACP
Fady Hannah-Shmouni, MD, DABIM, AHSCP, FRCPC

Additional Resources
American Society for Metabolic and Bariatric Surgery
Mayo Clinic

← More about Nondiabetic Hypoglycemia

Hypoglycemia can be a complication of bariatric surgery, due to metabolic changes that cause excess insulin production. It is often challenging to recognize as symptoms of hypoglycemia are similar to other disorders, such as generalized anxiety disorder or adrenal insufficiency.

Those who develop hypoglycemia after bariatric surgery, eating can triggers release of hormones which then causes a rapid drop in glucose. The problem is not typically the pancreas, but with the signals which instruct the pancreas to release insulin. Pancreas surgery is not recommended for post-bariatric hypoglycemia as it is not “cured” by removal of the pancreas.

Hypoglycemia can also be observed after other types of upper gastrointestinal surgery, such as ulcer surgery, removal of part of the esophagus, or reflux surgery such as fundoplication.

We do not understand why some individuals have hypoglycemia as a complication of surgery, whereas others do not. If you have a history of hypoglycemia and are considering bariatric surgery, please let your surgeon know, as this may influence decision making about surgery. Hypoglycemia after bariatric surgery typically occurs 1-3 hours after meals and sometimes with activity; it does not usually begin until more than 1 year after surgery.

  • An endocrinologist needs to make sure that other causes of hypoglycemia are not present, as these may be treated differently.
  • It is important to promptly treat hypoglycemia when it develops, so that your brain has enough glucose to function normally.
  • If you are diagnosed with hypoglycemia, please be sure your glucose level is not low before driving or other potentially hazardous activities.
  • Dietary and medication treatments are available to reduce the frequency and severity of hypoglycemia.

Hypoglycemia is not your fault.


Hypoglycemia = low blood sugar

Unawareness = reduced ability to detect hypoglycemia until brain function is impaired

Neuroglycopenia = symptoms related to inadequate glucose for the brain, such as confusion, blurred vision, difficulty speaking, loss of consciousness, falls, seizures

Dumping syndrome = a group of symptoms which occur after eating in individuals who have had upper gastrointestinal surgery (including bariatric surgery). Symptoms which can occur early after eating include racing heart, lightheadedness, abdominal cramps, and severe sleepiness or need to lie down. Hypoglycemia can sometimes occur as part of this syndrome.

Recommended Lifestyle Changes and Treatment

  • Start a meal plan which is aimed at preventing rapid increases in blood sugar and increases in the hormones which trigger rapid drops in glucose.
  • This includes avoiding liquids with meals, avoiding foods high in sugar or easily-digested carbohydrates.
  • Proteins and healthy fats should be emphasized.
  • Complete avoidance of carbohydrates is not desirable.
  • Avoid alcohol and caffeine
  • Take nutritional supplements to prevent nutrient deficiencies.
  • Since this is complicated, a dietician experienced in this condition should be seen.
  • If changes in meal plan are not enough to improve hypoglycemia, medications which reduce insulin and other hormones can be used.

Questions to ask your doctor

  • Could my symptoms be hypoglycemia?
  • If so, can you refer me to an endocrinologist to help with diagnosis and specialized treatment?
  • How to test my glucose?
  • Are there other tests I should consider?

Edited: June 2018