Magnitude and Variability of the Glucagon-Like Peptide-1 Response in Patients With Type 2 Diabetes up to 2 Years Following Gastric Bypass Surgery

OBJECTIVE: To characterize the magnitude and variance of the change of glucose and glucagon-like peptide-1 (GLP-1) concentrations, and to identify determinants of glucose control up to 2 years after gastric bypass (GBP). RESEARCH DESIGN AND METHODS: Glucose and GLP-1 concentrations were measured during an oral glucose challenge before and 1, 12, and 24 months after GBP in 15 severely obese patients with type 2 diabetes. RESULTS: Glucose area under the curve from 0 to 180 min (AUC(0–180)) started decreasing in magnitude (P < 0.05) 1 month after surgery. GLP-1 AUC(0–180) increased in magnitude 1 month after GBP (P < 0.05), with increased variance only after 1 year (P(σ)(2) ≤ 0.001). GLP-1 AUC(0–180) was positively associated with insulin AUC(0–180) (P = 0.025). CONCLUSIONS: The increase in variance of GLP-1 at 1 and 2 years after GBP suggests mechanisms other than proximal gut bypass to explain the enhancement of GLP-1 secretion. The association between GLP-1 and insulin concentrations supports the idea that the incretins are involved in glucose control after GBP.