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SURMOUNT-5: tirzepatide compared with semaglutide

Clinical Trial Update 3 min read
Reporting Source: New England Journal of Medicine (2025)

Source checked · External scientific review not documented

Research Summary

SURMOUNT-5 compared tirzepatide and semaglutide for weight loss in adults with obesity without diabetes. The open-label trial found greater average weight loss with tirzepatide at 72 weeks.

Key Findings & Takeaways
  • 751 adults were randomized in an open-label phase 3b trial.
  • Participants had obesity without type 2 diabetes; applicability to other populations requires separate evidence.
  • The trial compared maximum tolerated doses over 72 weeks.
  • This weight-loss comparison does not establish renal or cardiovascular benefits.

The original SURMOUNT-5 publication reports a randomized comparison of tirzepatide and semaglutide in 751 adults with obesity without type 2 diabetes.

What the trial studied

Participants received weekly injections at maximum tolerated doses: tirzepatide 10 or 15 mg, or semaglutide 1.7 or 2.4 mg. Follow-up lasted 72 weeks.

How to interpret the findings

Tirzepatide produced greater average weight reduction. The study was open-label and funded by Eli Lilly. Its population, doses, and endpoints matter: these results should not be presented as a universal comparison of all formulations or as proof of renal or cardiovascular benefit.

Citations & Primary Documents

  1. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity
    Aronne LJ et al. (2025) · New England Journal of Medicine, 393:26–36.
    Primary Source Document