The two most commonly performed bariatric surgical procedures, gastric bypass (GB) and sleeve gastrectomy (SG), induce diabetes remission before any significant weight loss. While the role of entero-insular axis after SG remains unknown, weight-independent glycemic effects of GB have been attributed to larger systemic appearance of glucose and incretin effect. We examined the effect of increasing endogenous incretins 2-3 fold with a DPP-4 inhibitor on glycemic effects of GB and SG. Glucose and islet-cell secretory responses were measured in 4 subjects with a history of GB, 4 with SG and 4 non-surgical controls (CN) during 50-gram oral glucose ingestion with and without 200 mg sitagliptin orally on two separate days. GB, SG, and CN groups were matched for BMI, FFM, HbA1c, age, fasting glucose and insulin levels; GB and SG were matched for weight loss and time postsurgery; none had diabetes. Compared to SG-treated subjects and controls, subjects with prior GB had lower prandial glycemia (AUCGlucose 3hr) (P < 0.001), and higher AUCGlucagon 3hr (P < 0.0001). The expected differences in prandial insulin response pattern to glucose ingestion among surgical and controls was observed; however, AUCInsulin 3hr and AUCC-peptide 3hr were similar between groups. Sitagliptin did not change AUCGlucose 3hr in GB-treated subjects, whereas the prandial glucose response was reduced by 21 ± 13 % in SG-treated and non-surgical controls by sitagliptin. Enhanced endogenous incretins diminished early glucagon (AUCGlucagon 1hr) in all 3 groups (P < 0.05), improved β-cell glucose sensitivity in CN (P < 0.05), but it had no effect on beta-cell function in GB or SG subjects. Sitagliptin had no effect on insulin clearance or insulin sensitivity in fasting or fed states. These findings indicate that glucose metabolism after SG, similar to non-operated controls, is enhanced by incretins, which are at maximum in GB group and thus not influenced by DPP-4 inhibition.


H. Honka: None. M. S. Rayas: Research Support; Self; National Center for Advancing Translational Sciences. R. A. Defronzo: Other Relationship; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Novo Nordisk, Research Support; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Speaker’s Bureau; Self; AstraZeneca, Novo Nordisk. A. Gastaldelli: Advisory Panel; Self; Boehringer Ingelheim International GmbH, Consultant; Self; Eli Lilly and Company, Inventiva Pharma, Research Support; Self; Gilead Sciences, Inc., Speaker’s Bureau; Self; Novo Nordisk. M. Salehi: None.


National Institutes of Health (TR002646); National Institute of Diabetes and Digestive and Kidney Diseases (DK105379)

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