Peptide Graded

Tirzepatide

Does Tirzepatide work?

Yes, in large controlled trials. The biggest weight trial had 2,539 people.

AStrong human evidenceFDA approvedas of 2026-10-27

Tirzepatide's weight-loss use rests on the SURMOUNT program of randomized placebo-controlled trials, the largest being SURMOUNT-1 with 2,539 adults, plus trials in type 2 diabetes, sleep apnea, weight maintenance and diabetes prevention. Every approved indication was granted on randomized data, so it grades A. 281415

SURMOUNT-1 randomized 2,539 adults with obesity or overweight and without diabetes. They got three tirzepatide doses or placebo for 72 weeks. Mean weight change was 15 percent, 19.5 percent and 20.9 percent across the doses. On placebo it was 3.1 percent. Half or more of participants on the two higher doses (50 and 57 percent) lost at least 20 percent of body weight. A three-year extension of the same trial included participants with prediabetes. It found that 1.3 percent progressed to type 2 diabetes on tirzepatide. On placebo it was 13.3 percent. 215

SURMOUNT-2 enrolled 938 adults with obesity and type 2 diabetes. They lost 12.8 percent and 14.7 percent of body weight at the two doses. On placebo they lost 3.2 percent. A 2024 network meta-analysis covered 28 trials in type 2 diabetes. Tirzepatide lowered HbA1c (the three-month blood sugar average) by 1.6 to 2.0 percentage points against placebo, depending on dose. It lowered weight more than semaglutide at each comparable dose. 68

Evidence checklist

  • Randomised controlled trial SURMOUNT programme; diabetes and sleep apnoea trials
  • Human study over 100 people SURMOUNT-1, 2,539 adults
  • More than one research group Article does not say who ran the trials
  • Clinical outcomes, not surrogate markers Weight, glucose, apnoea scores; outcomes not cited
  • Human safety data beyond case reports Large trials; GI effects, boxed thyroid warning

Read the full Tirzepatide page

More on Tirzepatide

Citations

  1. FDA 2025: Mounjaro (tirzepatide) prescribing information accessdata.fda.gov
  2. Jastreboff 2022, NEJM: Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) doi.org
  3. FDA 2025: Zepbound (tirzepatide) prescribing information accessdata.fda.gov
  4. FDA 2024: FDA approves first medication for obstructive sleep apnea fda.gov
  5. 2022, Int J Mol Sci: Tirzepatide, a dual GIP/GLP-1 receptor agonist, mechanism and metabolic effects doi.org
  6. 2024, Diabetologia: network meta-analysis of tirzepatide versus semaglutide in type 2 diabetes (28 RCTs) doi.org
  7. Aronne 2024, JAMA: Continued treatment with tirzepatide for maintenance of weight reduction (SURMOUNT-4) doi.org
  8. Garvey 2023, Lancet: Tirzepatide once weekly in adults with obesity and type 2 diabetes (SURMOUNT-2) doi.org
  9. FDA Drugs@FDA: Mounjaro NDA 215866 accessdata.fda.gov
  10. FDA 2026: Mounjaro label, pediatric type 2 diabetes accessdata.fda.gov
  11. FDA 2026: Mounjaro label, cardiovascular risk reduction accessdata.fda.gov
  12. FDA Drugs@FDA: Zepbound NDA 217806 accessdata.fda.gov
  13. FDA: Concerns with unapproved GLP-1 drugs used for weight loss fda.gov
  14. Malhotra 2024, NEJM: Tirzepatide for obstructive sleep apnea and obesity (SURMOUNT-OSA) doi.org
  15. Jastreboff 2024, NEJM: Tirzepatide for obesity treatment and diabetes prevention, three-year SURMOUNT-1 doi.org
  16. 2025, Cureus: tirzepatide versus semaglutide for weight loss, meta-analysis of seven direct comparative studies doi.org
  17. Rescalli 2026, Hum Psychopharmacol: tirzepatide initiation in lithium-treated bipolar disorder, renal and lithium safety over 12 months pubmed.ncbi.nlm.nih.gov

Reference information only, not medical advice. Drawn from the Tirzepatide article, fact-checked against the cited sources. No dosing anywhere on this site.