title: Glucose-stimulated insulin secretion in gastric bypass patients with hypoglycemic syndrome: no evidence for inappropriate pancreatic beta-cell function.
abstract: BACKGROUND
  Roux-en-Y gastric bypass surgery (RYGB) has been associated with a hypoglycemic syndrome characterized by postprandial hypoglycemia and hyperinsulinemia. The syndrome is believed to occur due to insulin hypersecretion from either pancreatic beta-cell hyperplasia or hyperfunction.
  
  
  METHODS
  Eight RYGB patients with hypoglycemic syndrome had insulin secretion rates determined during a 240-min graded intravenous glucose infusion. They were compared to 34 nondiabetic, nonsurgical individuals who were divided based on their insulin sensitivity status as measured by the insulin suppression test: insulin-sensitive (n = 8), insulin intermediate (n = 7), and insulin-resistant (n = 19).
  
  
  RESULTS
  RYGB patients had insulin concentrations and HOMA-IR similar to the insulin-sensitive reference group. In addition, integrated insulin secretion rates were comparable to the insulin-sensitive group and significantly lower than the insulin intermediate (p <or= 0.046) and insulin-resistant groups (p <or= 0.001). Pancreatic beta-cell sensitivity to glucose (slope relating glucose and ISR) was lowest in the RYGB group (p <or= 0.04).
  
  
  CONCLUSIONS
  Patients with hypoglycemic syndrome post-RYGB do not have generalized hypersecretion of insulin and appear to have appropriate insulin secretion rate in response to intravenous glucose.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. sunhkim@stanford.edu
authors.forename: Sun H
authors.initials: SH
authors.lastname: Kim
authors.forename: Fahim
authors.initials: F
authors.lastname: Abbasi
authors.forename: Cindy
authors.initials: C
authors.lastname: Lamendola
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Reaven
authors.forename: Tracey
authors.initials: T
authors.lastname: McLaughlin
mesh_terms: D000328:Adult; D019540:Area Under Curve; D005260:Female; D015390:Gastric Bypass / Q000009:adverse effects; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism*; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology; D007003:Hypoglycemia / Q000209:etiology* / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*
chemical_list: D007328:Insulin; D005947:Glucose