The purpose of this study is to learn more about the causes of hypoglycemia (low blood sugar).

This study involves coming to the Joslin Diabetes Center for 1 visit. For some participants, there may be an opportunity to take part in a 2nd visit.

At Visit 1 the following will take place:

  • Medical history, physical exam, EKG, and laboratory testing.
  • A blood sample will be collected for DNA.
  • Questionnaires about symptoms and health.
  • Providing a stool sample (collected at home) to assess bacteria in the intestine (microbiome).

If participating, Visit 2 involves:

  • Following a specific meal plan for 3 days prior to this visit, and arriving fasting.
  • Part of the physical examination will be repeated.
  • Meal test with a collection of blood samples measuring glucose levels, and a variety of hormones.
  • Instructions will be given on glucose monitoring and wearing 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. Compensation and parking costs will be provided.


  • Ages 18-65
  • Individuals who have a diagnosis of low blood sugars and no history of upper gastrointestinal surgery, and no current diagnosis of diabetes or pre-diabetes.
  • Individuals who have had gastric bypass and have developed low blood sugars.
  • Healthy individuals without a history of surgery (for comparison).


Cameron Cummings at (617) 309-4463 or  Hypoglycemiastudy [at]