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 4 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 18-70
  • 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] (Hypoglycemiastudy[at]joslin[dot]harvard[dot]edu)
Call: Cameron Cummings at (617) 309-4463