Semaglutide and tirzepatide are both compared constantly on weight loss, but a study published in early 2026 asked a different question: once you match similar patients and follow them in routine care, does one drug track with fewer heart attacks, strokes, and deaths than the other?
What the Study Did
The analysis, known as STEER, was published online in Diabetes, Obesity and Metabolism in January 2026. Researchers used real-world U.S. insurance claims data rather than a controlled trial, identifying adults aged 45 and older with overweight or obesity and established atherosclerotic cardiovascular disease, but without diabetes. Using propensity score matching, a statistical technique that pairs patients with similar baseline characteristics across the two drug groups, the researchers built two matched cohorts of 10,625 patients each, one on semaglutide and one on tirzepatide, for a combined 21,250 participants.
What They Found
Patients on semaglutide had a 29% lower risk of a broad cardiovascular composite endpoint (heart attack, stroke, or death from any cause) compared with the matched tirzepatide group, and a 22% lower risk of an expanded endpoint that also included heart failure hospitalization and coronary revascularization procedures. In a secondary analysis that censored patients at the point they stopped taking their medication, the gap was even larger, with reductions of 57% and 43% for the two endpoints respectively, suggesting the apparent advantage grew when patients stayed on therapy longer.
Why This Isn't the Final Word
It's worth being precise about what kind of evidence this is. STEER is an observational, retrospective study built from insurance claims, not a randomized controlled trial. Propensity score matching can balance the factors researchers measure and include in their model, but it cannot account for differences that aren't captured in claims data, things like diet, exercise habits, disease severity nuances, or why a particular doctor chose one drug over the other for a particular patient. That residual, unmeasured confounding is the standard limitation of real-world claims research, and it means the 29% and 22% figures describe an association in this dataset, not proof that switching a given patient from tirzepatide to semaglutide would lower their personal cardiovascular risk.
How This Fits With the Trial Evidence
Both drugs already have their own dedicated cardiovascular outcomes research from randomized trials, which carries more weight than observational comparisons between them. Semaglutide (as Wegovy) received FDA approval for reducing cardiovascular risk in adults with established heart disease and overweight or obesity, based on the large SELECT trial. Tirzepatide has its own cardiovascular outcomes data as well, including results from dedicated trials examining cardiovascular efficacy, and a separate mortality and morbidity trial in obesity (SURMOUNT-MMO) is ongoing. None of that existing trial evidence was a head-to-head comparison of the two drugs' cardiovascular outcomes against each other, which is exactly the gap a study like STEER is trying to informally address, with the caveats above.
The Bottom Line
A large, carefully matched real-world study found a meaningful association between semaglutide use and lower cardiovascular event rates compared with tirzepatide in this specific population: older adults with existing cardiovascular disease but not diabetes. That's a legitimate finding worth tracking, and it will likely motivate a genuine head-to-head randomized trial. It is not, by itself, strong enough evidence to conclude that semaglutide is the better choice for any individual patient's heart health, especially outside this specific population.
Talk to Your Doctor
Choosing between semaglutide and tirzepatide involves more than cardiovascular risk in isolation, including weight loss goals, side effect tolerance, insurance coverage, and other health conditions. This article summarizes one study; it isn't a recommendation to start, stop, or switch any medication, and that decision belongs with you and your physician.