Improvement in glucose metabolism after bariatric surgery : comparison of laparoscopic Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy : a prospective randomized trial

BACKGROUND: The exclusion of the proximal small intestine is thought to play a major role in the rapid improvement in the metabolic control of diabetes after gastric bypass. OBJECTIVE: In this randomized, prospective, parallel group study, we sought to evaluate and compare the effects of laparoscopic Roux-en-Y gastric bypass (LRYGB) with those of laparoscopic sleeve gastrectomy (LSG) on fasting, and meal-stimulated insulin, glucose, and glucagon-like peptide-1 (GLP-1) levels. METHODS: Thirteen patients were randomized to LRYGB and 14 patients to LSG. The mostly nondiabetic patients were evaluated before, and 1 week and 3 months after surgery. A standard test meal was given after an overnight fast, and blood samples were collected before and after food intake in both groups for insulin, GLP-1, glucose, PYY, and ghrelin concentrations. This trial was registered in www.clinicaltrials.gov (NCT00356213) before the first patient was randomized. RESULTS: Body weight and body mass index decreased markedly (P > 0.002) and comparably after either procedure. Excess BMI loss was similar at 3 months (43.3 +/- 12.1% vs. 39.4 +/- 9.4%, P < 0.36). After surgery, patients had markedly increased postprandial plasma insulin and GLP-1 levels, respectively (P > 0.01) after both of these surgical procedures, which favor improved glucose homeostasis. Compared with LSG, LRYGB patients had early and augmented insulin responses as early as 1-week postoperative; potentially mediating improved early glycemic control. After 3 months, no significant difference was observed with respect to insulin and GLP-1 secretion between the 2 procedures. CONCLUSION: Both procedures markedly improved glucose homeostasis: insulin, GLP-1, and PYY levels increased similarly after either procedure. Our results do not support the idea that the proximal small intestine mediates the improvement in glucose homeostasis.