Summary: In adults with obesity or overweight and type 2 diabetes, an indirect treatment comparison anchored on the SURMOUNT-2 and STEP 2 trials associated tirzepatide 10 and 15 mg once weekly with statistically significantly greater reductions in weight, BMI and HbA1c than semaglutide 2.4 mg once weekly, with a generally similar safety profile. No head-to-head trial was conducted, and the analysis was sponsored by the tirzepatide manufacturer.
PICO Summary
| Element | Detail |
|---|---|
| Population | Adults with type 2 diabetes and obesity or overweight (BMI 27 kg/m2 or higher, at least one prior unsuccessful dietary weight-loss attempt, HbA1c 7 to 10 percent on stable therapy). Populations were drawn indirectly from the SURMOUNT-2 (tirzepatide) and STEP 2 (semaglutide) randomised, placebo-controlled trials; baseline characteristics were judged sufficiently similar for comparison. |
| Intervention | Tirzepatide 10 mg and 15 mg once weekly, subcutaneous, adjunct to a reduced-calorie diet and increased physical activity (efficacy estimated indirectly via the SURMOUNT-2 trial arms). |
| Comparison | Semaglutide 2.4 mg once weekly, subcutaneous, adjunct to diet and exercise (estimated indirectly via the STEP 2 trial arms). The two trials were linked through their shared placebo arms using a Bucher indirect treatment comparison; there was no direct head-to-head randomisation. |
| Outcome | Tirzepatide 10 and 15 mg were associated with statistically significantly greater reductions in weight, BMI and HbA1c than semaglutide 2.4 mg. For percent weight loss, reported mean differences favouring tirzepatide were approximately 2.57 percent (10 mg) and 4.79 percent (15 mg) versus semaglutide (p less than 0.01 for both). Tirzepatide 15 mg was also associated with higher odds of achieving 5 percent or greater and 15 percent or greater weight loss and with significant improvements in waist circumference, fasting plasma glucose and triglycerides; lipid and blood-pressure differences were non-significant trends. Both doses showed a generally comparable safety profile. The PubMed abstract did not report full 95 percent confidence intervals, absolute risk reductions or numbers needed to treat for all endpoints, so the estimates above should be read as indirect, hypothesis-generating associations. |
Tirzepatide vs semaglutide in T2D obesity
Bucher indirect comparison · T2D + obesity · ~72 wk
In an industry-sponsored indirect comparison, tirzepatide 10 and 15 mg were associated with greater weight and HbA1c reduction than semaglutide 2.4 mg. There was no head-to-head trial, so treat this as hypothesis-generating, not proof of superiority.
Expert Commentary
This analysis is best understood as an indirect treatment comparison, not a head-to-head trial. The efficacy and safety of tirzepatide and semaglutide were never measured against each other directly; instead, their respective placebo-controlled trials were anchored through a shared placebo arm using the Bucher method. Such comparisons are vulnerable to unmeasured differences in trial conduct, populations and endpoints, and they sit lower in the evidence hierarchy than a randomised head-to-head study. The reported direction, with tirzepatide associated with greater weight, BMI and HbA1c reduction, is consistent with the pharmacology of a dual GIP and GLP-1 receptor agonist and with prior indirect analyses, which lends some coherence. The most important limitation, however, is sponsorship: the study was funded by the tirzepatide manufacturer, with several authors employed by that company, so the framing and selection of favourable endpoints warrant cautious interpretation. The absence of full confidence intervals in the abstract further limits how firmly the magnitude of benefit can be judged. Can I use this with my patients? Cautiously, as supportive context rather than proof, for a patient with type 2 diabetes and obesity in whom you are already weighing tirzepatide against semaglutide; it should not be presented as definitive evidence of superiority. A direct, independently funded head-to-head trial with patient-important outcomes is needed before any firm ranking is justified.
References
Ciudin A, Johansson E, Zimner-Rapuch S, Dimitriadis GK, Bertrand M, Curteis T, et al. Indirect comparative efficacy and safety of tirzepatide 10 and 15 mg versus semaglutide 2.4 mg for the management of obesity and overweight in patients with type 2 diabetes. Diabetes Obes Metab. 2025;27(9):4709-4719. doi:10.1111/dom.16508