Greater early postprandial GLP-1 increase after Roux-en-Y than one-anastomosis gastric bypass, with unchanged secretin: a randomized controlled trial

BACKGROUND: Few studies have compared gut hormone responses between bariatric procedures. This study compared Roux-en-Y and one-anastomosis gastric bypass (RYGB and OAGB) regarding glucagon-like peptide-1 (GLP-1), secretin, and glucose-insulin dynamics. METHODS: This study included 41 participants (RYGB: n = 21, OAGB: n = 20) from the randomized RYSA trial with similar amounts of bypassed intestine between the procedures. Plasma GLP-1, secretin, glucose, insulin, and C-peptide were measured during a 360-min mixed-meal test before, and at 6- and 12-months after surgery. Outcomes included total and early-phase (0-60 min) areas under the curve (AUCs) and peak concentrations. Visual analogue scales were used to measure hunger and satiety. RESULTS: Both procedures resulted in ~25% weight loss and marked metabolic improvements over 12 months. While fasting GLP-1 remained largely unchanged, postprandial concentrations rose markedly at 6 months (total AUC increase in RYGB: ~330%, OAGB: ~259%; p < 0.001) and remained elevated at 12 months. The increases in early-phase GLP-1 AUC were 31% higher in RYGB than OAGB at 6 months (95% CI: 3 to 68; p = 0.030) and 25% higher at 12 months (95% CI: -2 to 59; p = 0.072). Peak GLP-1 increases were significantly higher ( ~ 32%) after RYGB at both follow-ups (p < 0.05). Postprandial reduction in hunger was greater after RYGB than OAGB from baseline to 12 months. Fasting or postprandial secretin concentrations showed no significant changes. Both operations were associated with decreased fasting glucose, insulin, and C-peptide; increased early glucose but decreased glucose total AUCs; and increased insulin early AUC and C-peptide total and early AUCs. Glucose early-phase AUC and peak concentration increases were greater after RYGB than OAGB. CONCLUSIONS: Both RYGB and OAGB lead to markedly enhanced postprandial GLP-1 responses, with no corresponding change in secretin levels. RYGB produces higher early postprandial increases in GLP-1 and glucose than OAGB, demonstrating that procedural differences can influence gut hormone and glucose responses.