Research
The trials behind tirzepatide
Tirzepatide is one of the better-evidenced medications a reader of this site will encounter, and almost none of that evidence is about what the price index sells. This corpus separates the two.
Every trial below was located on PubMed and its PMID resolved before anything here was written. Each figure is reported with the comparator it was measured against, the number of weeks it took, and the number of participants it came from.
- Trials in this corpus
- 4
- Participants across them
- 5,839
- Longest trial, in weeks
- 88
The trials in this corpus
- SURMOUNT-1
20.9%of body weight lost at the top dose, against 3.1% on placebo
At week 72 mean weight change was -15.0% on 5 mg, -19.5% on 10 mg and -20.9% on 15 mg, against -3.1% on placebo. In the 15 mg group 57% of participants lost 20% of body weight or more, against 3% on placebo.
- Participants
- 2,539
- Weeks
- 72
- Against
- Placebo
Jastreboff AM, New England Journal of Medicine 2022 · PMID 35658024
- SURPASS-2
2.30percentage points off HbA1c, against 1.86 on semaglutide
Glycated hemoglobin fell by 2.01, 2.24 and 2.30 percentage points on tirzepatide 5 mg, 10 mg and 15 mg, against 1.86 points on semaglutide 1 mg. Tirzepatide was noninferior and superior at every dose. Weight fell further on tirzepatide, by an estimated 1.9 kg, 3.6 kg and 5.5 kg respectively.
- Participants
- 1,879
- Weeks
- 40
- Against
- Semaglutide 1 mg once weekly
Frías JP, New England Journal of Medicine 2021 · PMID 34170647
- SURMOUNT-4
14.0%regained by those switched to placebo, against 5.5% lost on tirzepatide
Between week 36 and week 88 weight changed by -5.5% on continued tirzepatide and by +14.0% on placebo, a difference of 19.4 percentage points. Participants had lost a mean 20.9% during the lead-in; 89.5% of those continuing held at least 80% of that loss, against 16.6% of those switched to placebo.
- Participants
- 670
- Weeks
- 88
- Against
- Placebo, by withdrawal of tirzepatide
Aronne LJ, JAMA 2024 · PMID 38078870
- SURMOUNT-5
20.2%of body weight lost, against 13.7% on semaglutide
At week 72 weight fell by 20.2% on tirzepatide and 13.7% on semaglutide. Waist circumference fell by 18.4 cm and 13.0 cm respectively.
- Participants
- 751
- Weeks
- 72
- Against
- Semaglutide at 1.7 mg or 2.4 mg once weekly
Aronne LJ, New England Journal of Medicine 2025 · PMID 40353578
What they measured
Three of the four trials report weight change per study arm. Each chart below draws only figures that appear in that trial’s own published abstract, beside the comparator it was measured against — which is the part most coverage drops.
Filled bars are tirzepatide; the outlined bar is placebo. Read from the published abstract, PMID 35658024.
Filled bar is tirzepatide; the outlined bar is placebo, by withdrawal of tirzepatide. Read from the published abstract, PMID 38078870.
Filled bar is tirzepatide; the outlined bar is semaglutide at 1.7 mg or 2.4 mg once weekly. Read from the published abstract, PMID 40353578.
The corpus at a glance
| Trial | Compared against | Participants | Weeks | Published |
|---|---|---|---|---|
| SURMOUNT-1 | Placebo | 2,539 | 72 | New England Journal of Medicine, 2022 |
| SURPASS-2 | Semaglutide 1 mg once weekly | 1,879 | 40 | New England Journal of Medicine, 2021 |
| SURMOUNT-4 | Placebo, by withdrawal of tirzepatide | 670 | 88 | JAMA, 2024 |
| SURMOUNT-5 | Semaglutide at 1.7 mg or 2.4 mg once weekly | 751 | 72 | New England Journal of Medicine, 2025 |
References
- Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387(3):205-216. PMID: 35658024. NCT04184622.
- Frías JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. New England Journal of Medicine. 2021;385(6):503-515. PMID: 34170647. NCT03987919.
- Aronne LJ, et al. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial. JAMA. 2024;331(1):38-48. PMID: 38078870. NCT04660643.
- Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. New England Journal of Medicine. 2025;393(1):26-36. PMID: 40353578. NCT05822830.