The purpose of this study is to learn more about the causes of hypoglycemia (low blood sugar) which develops in some individuals who have had bariatric surgery.

This study involves visits (over 2 months) to Joslin Diabetes Center. Over the course of those 4 visits, the following will occur:

  • Medical history, physical exam, EKG, laboratory testing, and wear of a continuous glucose monitoring device for 10 days at home
  • Keeping a log of food, activity, and glucose levels over the same 10 day period while also wearing a FitBit activity tracker.
  • Providing a stool sample (collected at home) to assess bacteria in the intestine(microbiome)
  • Following a specific meal plan for 3 days before Visits 2, 3, & 4, and arrive fasting to those visits.
  • Meal test with a collection of blood samples measuring glucose levels and a variety of hormones
  • Injection of the hormone glucagon and measuring glucose and hormone levels
  • Measuring hormone levels while we gradually lower glucose levels, as well as during a controlled period of a low glucose level.


  • Ages 18-65
  • Individuals who have had gastric bypass without symptoms of low blood sugar
  • Individuals who have had gastric bypass and have developed low blood sugars
  • Healthy individuals without a history of surgery (for comparison)

Compensation and parking costs will be provided.

Email: Hypoglycemiastudy [at]
Call: Alexa Puleio at (617) 309-4463