Comparative effectiveness of metabolic bariatric surgery versus incretin-based and medical therapies for weight loss and glycemic outcomes: a systematic review and meta-analysis

<ns5:p> Background Metabolic bariatric surgery and incretin-based pharmacotherapies are established treatment options for obesity and type 2 diabetes mellitus (T2D). However, their comparative effectiveness has evolved alongside advances in obesity pharmacotherapy. This systematic review and meta-analysis evaluated the effectiveness of metabolic bariatric surgery versus medical and incretin-based therapies for weight loss and glycemic outcomes. Methods A systematic search of PubMed, Scopus, and Web of Science was conducted from inception through January 2026. Comparative studies evaluating metabolic bariatric surgery against medical or incretin-based therapies in adults with obesity and/or T2D were included. Continuous outcomes were pooled using random-effects models and standardized mean differences (SMDs). Prespecified subgroup analyses were performed according to treatment era, study design, and follow-up duration. Results Seven studies involving 1,872 participants met the inclusion criteria. Overall, metabolic bariatric surgery resulted in significantly greater weight loss than medical or incretin-based therapies (SMD = −2.02; 95% CI, −2.59 to −1.45), although heterogeneity was substantial (I <ns5:sup>2</ns5:sup> = 74.7%). Treatment-era stratification reduced heterogeneity within contemporary studies and demonstrated a progressive narrowing of effect sizes over time. Surgery also achieved greater HbA1c reduction (SMD = −0.63; 95% CI, −0.88 to −0.37) with no observed heterogeneity (I <ns5:sup>2</ns5:sup> = 0%). Sensitivity analyses excluding studies at serious risk of bias confirmed the robustness of the primary findings for both weight loss (SMD = −1.70; 95% CI, −1.84 to −1.57) and HbA1c reduction (SMD = −0.81; 95% CI, −1.18 to −0.43). Secondary metabolic outcomes showed no consistent differences between interventions. Conclusion Metabolic bariatric surgery remains associated with superior weight loss and glycemic improvement compared with medical and incretin-based therapies. Although modern pharmacologic treatments have narrowed the historical efficacy gap, surgery continues to provide the most consistent overall benefit across available comparative evidence. </ns5:p>