Mapping the hormone behind Post-Surgery blood sugar crashes

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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.