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Effects of Gastric Bypass Surgery on Insulin Resistance and Insulin Secretion in Nondiabetic Obese Patients
Author(s) -
PromintzerSchifferl Miriam,
Prager Gerhard,
Anderwald Christian,
Mandl Martina,
Esterbauer Harald,
ShakeriLeidenmühler Soheila,
Pacini Giovanni,
Stadler Marietta,
Bischof Martin G.,
Ludvik Bernhard,
Luger Aanton,
Krebs Michael
Publication year - 2011
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1038/oby.2011.92
Subject(s) - medicine , postprandial , endocrinology , insulin , glucagon like peptide 1 , insulin resistance , incretin , gastric bypass surgery , ingestion , glucose clamp technique , diabetes mellitus , area under the curve , c peptide , gastric inhibitory polypeptide , glucose uptake , glucagon , gastric bypass , obesity , weight loss , type 2 diabetes , pancreatic hormone
Roux‐en‐Y‐Gastric‐Bypass (RYGB) reduces overall and diabetes‐specific mortality by 40% and over 90%. This study aims to gain insight into the underlying mechanisms of this effect. We evaluated time‐courses of glucose, insulin, C‐peptide, and the incretin glucagon like peptide‐1 (GLP‐1) following an oral glucose load. Insulin‐sensitivity was measured by a hyperinsulinemic‐isoglycemic‐clamp‐test; glucose‐turnover was determined using d ‐[6,6‐ 2 H 2 ] glucose. Examinations were performed in six nondiabetic patients with excess weight before (PRE: BMI: 49.3 ± 3.2 kg/m 2 ) and 7 months after RYGB (POST: BMI: 36.7 ± 2.9 kg/m 2 ), in a lean (CON: BMI: 22.6 ± 0.6 kg/m 2 ) and an obese control group (CONob) without history of gastrointestinal surgery (BMI: 34.7 ± 1.2 kg/m 2 ). RYGB reduced fasting plasma concentrations of insulin and C‐peptide ( P < 0.01, respectively) whereas fasting glucose concentrations remained unchanged. After RYGB increase of C‐peptide concentration following glucose ingestion was significantly higher compared to all other groups (dynamic‐area under the curve (Dyn‐AUC): 0–90 min: POST: 984 ± 115 ng·min/ml, PRE: 590 ± 67 ng·min/ml, CONob: 440 ± 44 ng·min/ml, CON: 279 ± 22 ng·min/ml, P < 0.01 respectively). Early postprandial increase of glucose concentration was however not affected. GLP‐1 concentrations following glucose ingestion were sixfold higher after RYBG than before ( P = 0.01). Insulin‐stimulated glucose uptake tended to increase postoperatively (M‐value: PRE: 1.8 ± 0.5, POST: 3.0 ± 0.3, not significant (n.s.)). Endogenous glucose production (EGP) was unaffected by RYGB. Hepatic insulin resistance index improved after RYGB and was then comparable to both control groups (PRE: 29.2 ± 4.3, POST: 12.6 ± 1.1, P < 0.01). RYGB results in hyper‐secretion of insulin and C‐peptide, whereas improvements of insulin resistance are minor and seem to occur rather in the liver and the adipose tissue than in the skeletal muscle.