Glucose-stimulated insulin secretion in gastric bypass patients with hypoglycemic syndrome: no evidence for inappropriate pancreatic beta-cell function.
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.
Kim
Sun H
SH
Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. sunhkim@stanford.edu
Abbasi
Fahim
F
Lamendola
Cindy
C
Reaven
Gerald M
GM
McLaughlin
Tracey
T
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*
D007328:Insulin; D005947:Glucose