Comparison of Hormonal Response to a Mixed-Meal Challenge in Hypoglycemia After Sleeve Gastrectomy vs Gastric Bypass

CONTEXT: Exaggerated postprandial incretin and insulin responses are well documented in postbariatric surgery hypoglycemia (PBH) after Roux-en-Y gastric bypass (RYGB). However, less is known about PBH after sleeve gastrectomy (SG). OBJECTIVE: We sought to compare meal-stimulated hormonal response in those with PBH after SG vs RYGB. METHODS: We enrolled 23 post-SG (12 with and 11 without PBH) and 20 post-RYGB (7 with and 13 without PBH) individuals who underwent bariatric surgery at our institution. PBH was defined as plasma glucose less than 60 mg/dL on 4-hour mixed-meal tolerance test (MTT). Islet and incretin hormones were compared across the 4 groups. RESULTS: Participants (N = 43) were on average 5 years post surgery, with a mean age of 48 years, mean preoperative body mass index of 48.4, 81% female, 61% White, and 53% post SG. Regardless of PBH, the SG group showed lower glucose, glucagon, and glucagon-like peptide 1 (GLP-1) responses to MTT and similar insulin and glucose-dependent insulinotropic polypeptide (GIP) responses compared to the RYGB group. Among those with PBH, the SG group following the MTT showed a lower peak glucose (P = .02), a similar peak insulin (90.3 mU/L vs 171mU/L; P = .18), lower glucagon (P < .01), early GLP-1 response (AUC0-60 min; P = .01), and slower time to peak GIP (P = .02) compared to PBH after RYGB. CONCLUSION: Among individuals with PBH, those who underwent SG were significantly different compared to RYGB in meal-stimulated hormonal responses, including lower glucagon and GLP-1 responses, but similar insulin and GIP responses. Future studies are needed to better understand the differential contribution of insulin and non-insulin-mediated mechanisms behind PBH after SG vs RYGB.