Indirect Comparative Efficacy and Safety of Tirzepatide Versus Oral Semaglutide for the Treatment of Overweight and Obesity.
This study aimed to indirectly compare the efficacy and safety of injectable tirzepatide (a dual GIP/GLP-1 receptor agonist) with oral semaglutide (a GLP-1 receptor agonist) for weight management in adults with overweight or obesity but without type 2 diabetes. Because no head-to-head trial exists, researchers used multilevel network meta-regression (ML-NMR) to adjust for baseline differences in sex, ethnicity, and outcome measures between two pivotal trials: SURMOUNT-1 (tirzepatide, 72 weeks) and OASIS 1 (oral semaglutide, 68 weeks). After adjustment, the analysis found that tirzepatide at two of the three doses studied was associated with statistically significantly greater reductions in body weight and waist circumference compared with oral semaglutide. Tirzepatide was also associated with higher odds of achieving clinically meaningful weight-loss thresholds (≥5%, ≥10%, ≥15%, and ≥20% body weight reduction). Cardiometabolic outcomes and safety profiles were reported as improved or broadly comparable for tirzepatide versus oral semaglutide. Key limitations include the indirect nature of the comparison, differences in trial duration and populations, and the inability to fully control for all confounders across separate trials. The findings should be interpreted cautiously pending direct head-to-head evidence.
Why this grade: Although based on large human RCT data, the comparison is entirely indirect via ML-NMR across two separate trials with differing durations and populations, precluding the causal certainty of a direct head-to-head RCT.
Aims Tirzepatide, an injectable glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist (RA), is approved for weight management in several regions. Oral GLP-1 RAs, such as semaglutide, are under investigation to improve convenience, acceptance and adherence versus injectable formulations. Currently, no studies have compared the efficacy and safety of tirzepatide with oral semaglutide for weight management. This study aimed to indirectly compare the efficacy and safety of weekly injectable tirzepatide 5, 10 and 15 mg for weight management in obesity and overweight versus daily oral semaglutide 50 mg. Materials and methods Pivotal trials SURMOUNT-1 (tirzepatide, Week 72) and OASIS 1 (oral semaglutide, Week 68) were compared using multilevel network meta-regression (ML-NMR) to adjust for differences in sex, ethnicity and outcome baselines between trial populations. Participants were adults without type 2 diabetes and with obesity (BMI ≥ 30 kg/m 2 ), or overweight (BMI ≥ 27 kg/m 2 ) with ≥ 1 obesity-related complication. Results Tirzepatide 10 and 15 mg were associated with statistically significantly greater reductions in weight (mean difference: -4.48% [-6.35, -2.61] and -5.59% [-7.52, -3.77]) and waist circumference (-3.60 cm [-5.59, -1.72] and -4.32 cm [-6.30, -2.40]), and higher odds of achieving ≥ 5%/10%/15%/20% weight reduction compared with oral semaglutide. Cardiometabolic benefits and safety profiles were improved or generally comparable for tirzepatide versus oral semaglutide. Conclusions This ML-NMR provides an indirect comparison of injectable tirzepatide with oral semaglutide for weight management. Tirzepatide was associated with statistically significantly greater weight and waist circumference reduction versus oral semaglutide and improved or similar cardiometabolic benefits and safety.
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