The contribution of GLP-1 on glucose control after gastric bypass (GBP) is not fully elucidated.

Hypotheses: The improvement in β-cell glucose sensitivity (BCGS) to oral glucose after GBP is GLP-1 mediated, weight loss independent, and varies according to diabetes (T2D) remission status; The administration of exendin 9-39 (EX9), a GLP-1 receptor blocker, has minimal effect on blood glucose.

Methods: Patients with T2D (n=29) underwent a 75 g OGTT prior to and at 3, 12 and 24 months (M) after GBP. Glucose, insulin secretion rates (ISR), BCGS, and glucagon were measured with and without EX9. The cohort was retrospectively divided into 3 groups based on T2D remission status determined at the latest study time point (24 or 12M): remitters (REM, n=5), persistent T2D (P-T2D, n=8), impaired (IGT, n=16).

Results: Prior to GBP, patients were 42.9±8.3y old, had a BMI of 42.4±4.6 kg/m2, 7.7±7.3 y known T2D duration, an HbA1c of 7.8±1.1% (35% on insulin) and an HOMA-IR of 11.5±5.8. Both magnitude and temporal increases in BCGS varied according to remission status: greater (up to 6.5 fold, p<0.03) and sustained in REM, variable in IGT (∼3 fold, p<0.01), minimal and only transient (3M, p=0.014) in P-T2D. These differences were not explained by weight-loss since it did not differ between the 3 groups at any time. EX9 reversed the effect of GBP on ISR at 3, 12 and 24M (p<0.003); it further enhanced the rise in post-prandial glucagon, but this effect was only significant at 3M (p=0.005). Both effects varied in magnitude overtime and by remission status. Glucose improved after GBP, as expected; EX9 decreased glucose levels at 3M in the whole cohort (p<0.001), but had no effect on glucose at 12 and 24M. EX9 increased significantly, albeit minimally, glucose at 120 and/or 180 minutes during the OGTT in REM and IGT, but not in P-T2D.

Conclusions: Our data suggest that the effect of endogenous GLP-1 on pancreatic endocrine function and glucose varies with time and according to remission status after GBP.


M.A. Prasad: None. A. Shah: None. V.M. Mark: None. N. Nair: None. J.J. Holst: Advisory Panel; Self; AstraZeneca, Merck Sharp & Dohme Corp., Novo Nordisk A/S, Zealand Pharma A/S. Other Relationship; Spouse/Partner; Antag Therapeutics.


National Institutes of Health (R01DK67561, DK007559, P30DK26687, UL1RR024156, UL1TR000040, F32DK113747)

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