The short answer
Tirzepatide produced greater weight reduction than semaglutide 1 mg in this diabetes trial. The comparison applies to the doses and population studied, not every use of either medicine.
Who took part?
Researchers randomized 1,879 adults with type 2 diabetes to weekly tirzepatide 5, 10 or 15 mg, or semaglutide 1 mg, for 40 weeks. The trial was open-label. Its primary outcome was blood-sugar control; weight was another measured outcome.
Kilograms more lost, not total weight loss
Original visual based on the study.
| Group or measure | Result |
|---|---|
| Tirzepatide 5 mg | 1.9 kg |
| Tirzepatide 10 mg | 3.6 kg |
| Tirzepatide 15 mg | 5.5 kg |
What changed?
Compared with semaglutide 1 mg, estimated additional weight reduction was:
1.9 kg with tirzepatide 5 mg.
3.6 kg with tirzepatide 10 mg.
5.5 kg with tirzepatide 15 mg.
These are between-group differences, not total weight losses.
What were the trade-offs?
Digestive side effects were common in both groups. Serious adverse events were reported in 5–7% across tirzepatide groups and 3% with semaglutide; reports do not establish that the medicine caused each event.
The useful takeaway
Check the comparator dose before interpreting a headline. SURPASS-2 did not test semaglutide 2.4 mg or people without diabetes. SURMOUNT-5 studied a different population and regimens.
Sources
Frías and colleagues, NEJM, 2021. Funded by Eli Lilly.