Objectives: One-anastomosis gastric bypass (OAGB) is as effective as Roux-en-Y gastric bypass (RYGB) regarding weight loss and diabetes remission. However, there are no data on gut hormone secretions after OAGB. The aim of this study was to compare fasting and postprandial secretions of gut and pancreatic hormones in OAGB versus RYGB patients.

Design and methods: Twenty-nine patients, 16 OAGB- and 13 RYGB-operated, underwent a liquid mixed-meal tolerance test at 2 years’ post-surgery. Blood was sampled before and 15, 30, 60, 90, and 120 min after meal for plasma measurement of glucose, C-peptide, insulin, glucagon, GLP-1, GIP, GLP-2, PYY, and ghrelin.

Results: Percentage of total weight loss 2 years post-surgery were -33.9 ± 1.8% for OAGB and -31.2 ± 1.6% for RYGB (p = 0.6). Four patients with persistent diabetes were excluded for further analysis. Fasting and postprandial glucose levels (peaks and area under curve values) were similar between groups. HOMA index was lower in the OAGB group (0.8 ± 0.1 vs 1.3 ± 0.2 in RYGB, p < 0.05). Levels of C-peptide (or insulin) measured at 30 min were significantly lower in OAGB vs RYGB patients (6.9 ± 0.5 vs 9.7 ± 1.1 µg/l, p < 0.05). No difference was observed between OAGB and RYGB groups for GLP-1, GLP-2, PYY, or ghrelin postprandial secretions, but GIP tended to be lower in OAGB vs RYGB patients (756 ± 155 vs 1100 ± 188 pg/ml for postprandial peak concentrations, p = 0.06).

Conclusions: This is the first clinical study showing that OAGB procedure, like RYGB, results in high postprandial secretions of gut hormones, in particular GLP-1.