Heart attacks, yes. Strokes, not in this cohort. Among 52,971 adults with type 2 diabetes and established cardiovascular disease, tirzepatide initiators had major adverse cardiovascular events in 2.9% against 4.4% on a cardiovascular-neutral comparator. That is a hazard ratio of 0.68 and a number needed to treat of 70.
Split the composite and the two halves part company. Heart attack fell, at a hazard ratio of 0.67 (95% CI 0.52 to 0.87). Ischemic stroke did not, at 0.91 (95% CI 0.64 to 1.28), where the number needed to treat works out at 2,500. A composite that moves is not every component moving, and this one names which.
A randomized trial reached a similar place from the other direction. Tirzepatide against dulaglutide in 13,299 people met noninferiority and missed superiority, at P=0.09 [2]. Matching an older drug is not beating it.
The study here also did something most observational work skips: it ran two negative control outcomes, and neither showed an association. That is a check on residual confounding rather than an assumption that none exists.
Most observational drug comparisons on this site fail on the same problem: people who get the newer drug differ from people who do not, in ways no adjustment fully captures. This one built three defenses against that, and it is worth reading for the method as much as the result [1]. It is the standard this site applied in the study that checked its own work.
First, the comparator. Tirzepatide initiators, 35,353 of them, were not compared against untreated people. The comparator was sitagliptin initiators (17,618) — a drug chosen because its cardiovascular effect is neutral, making it a proxy for placebo among people who are being actively treated. Second, propensity score overlap weighting balanced baseline characteristics. Third, the authors tested two negative control outcomes, lumbar radiculopathy and abdominal hernia, which no drug in this class should affect. Neither showed an association.
On the result, major adverse cardiovascular events occurred in 2.9% of the tirzepatide group and 4.4% of the sitagliptin group at one year. That is a risk difference of 1.4 percentage points, a number needed to treat of 70, and a hazard ratio of 0.68. Heart attack drove it, at a hazard ratio of 0.67 and an NNT of 130. That is an absolute gain of the kind this site keeps separating from relative ones in sixteen percent lower, six hundredths of a point.
Two findings sit outside the cardiovascular story and deserve reporting without explanation. Infections requiring hospital admission were lower on tirzepatide (HR 0.64, 95% CI 0.55 to 0.75, NNT 48), as was infection-related mortality (HR 0.40, 95% CI 0.26 to 0.61). All-cause mortality came in at 0.55 (95% CI 0.42 to 0.72). Those are large and this site will not speculate about why they appear.
The limits are ordinary and real. Follow-up ran one year and was censored at discontinuation or switching, so this measures the first year of continuous use rather than a durable effect. And claims data records prescriptions and diagnoses, not people. What makes the study unusual is what its authors did next. They asked their own data to prove it was not lying — the practice this site wants more of, and rarely gets, as in the result extrapolated to everyone.