Post-Prandial Carbohydrate Metabolism in Individuals With and Without Post-Bariatric Surgery Hypoglycemia (PBH)

Inclusion Criteria:

* Age 18-70 years of age, inclusive, at screening.
* Willingness to provide informed consent and follow all study procedures, including attending all scheduled visits.
* Males or females at least 2 years following Roux-en-Y gastric bypass (RYGB)
* For patients recruited to PBH group: diagnosed with ongoing PBH, with documented episodes of hypoglycemia, and history of fulfillment of Whipple's triad.

Exclusion Criteria:

* Documented hypoglycemia occurring only in the fasting state (\>12 hours fast);
* Current diabetes, defined as hemoglobin A1c \>6.5% or use of diabetes medications, except for acarbose or miglitol;
* Chronic kidney disease stage 4 or 5 (including end-stage renal disease);
* Hepatic disease, including serum ALT or AST greater than 2 times the upper limit of normal; hepatic synthetic insufficiency as defined as serum albumin \< 3.0 g/dL; or serum bilirubin \> 2.0;
* Congestive heart failure, NYHA class II, III or IV;
* History of myocardial infarction, unstable angina or revascularization within the past 6 months.
* Two or more risk factors for coronary artery disease including diabetes, uncontrolled hypertension, uncontrolled hyperlipidemia, and active tobacco use.
* History of recurrent syncope (unrelated to hypoglycemia) or active diagnosis of a cardiac arrhythmia;
* Current administration of β-blocker therapy;
* History of a cerebrovascular accident;
* Seizure disorder (other than with suspect or documented hypoglycemia);
* Active treatment with long-acting (LAR) octreotide or pasireotide;
* Active malignancy, except basal cell or squamous cell skin cancers;
* Personal or family history of pheochromocytoma or disorder with increased risk of pheochromocytoma (MEN 2, neurofibromatosis, or Von Hippel-Lindau disease);
* Known insulinoma;
* Major surgical operation within 30 days prior to screening;
* Clinically significant anemia as defined as a hematocrit \< 33%;
* Bleeding disorder, treatment with warfarin, or platelet count \<50,000;
* Blood donation (1 pint of whole blood) within the past 2 months;
* Active alcohol abuse or substance abuse;
* Current administration of oral or parenteral corticosteroids;
* Pregnancy and/ or lactation: For persons of childbearing potential: there is a requirement for a negative urine pregnancy test before any procedures.
* Not enrolled in another study that uses an investigational drug for this condition.