Semaglutide cuts major heart events by 19%, but many stop taking it

Heart disease is the thing most likely to shorten the life of someone with type 2 diabetes, so modern glucose drugs are increasingly judged on hard cardiovascular outcomes rather than blood sugar alone. GLP-1 receptor agonists have built a reputation for improving those outcomes as well as lowering glucose. Semaglutide is the newest member of that class, and according to the authors its cardiovascular effects had not yet been systematically reviewed. With the drug now used at enormous scale, knowing whether it actually prevents heart attacks and cardiovascular deaths matters far beyond the clinic.

The reviewers pre-registered their protocol and searched PubMed, Scopus and Web of Science on February 26, 2024 for randomised controlled trials testing semaglutide against placebo on cardiovascular outcomes. Four trials qualified, covering 27,617 people in total, with 13,809 assigned to semaglutide and 13,808 to placebo. Results were pooled with a random effects model, and each trial's quality was checked with the Cochrane risk of bias tool. The outcomes examined included major adverse cardiovascular events, cardiovascular death, heart attack, stroke, hospital admissions and treatment discontinuation.

The headline result was a significantly lower risk of major adverse cardiovascular events on semaglutide, a relative risk of 0.81, with the four trials in near-perfect agreement. Benefits also showed up for cardiovascular death and non-fatal heart attack specifically. Semaglutide did not significantly reduce non-fatal stroke, hospitalisations for heart failure, or admissions for unstable angina. Serious adverse events overall were less common on the drug, with a relative risk of 0.91. The flip side was discontinuation: people on semaglutide were substantially more likely to stop treatment, a relative risk of 1.67, though the trials varied widely on this point.

This review extends the cardiovascular story already told for the GLP-1 drug class to its newest and most widely used member, and the consistency across trials strengthens the case. It also complicates the simple success narrative: the authors argue that the high rate of treatment discontinuation has been underemphasised and deserves more cautious interpretation against the benefits. Open questions remain about why stroke and heart failure admissions did not move, which groups of patients gain the most, and whether real-world users stay on the drug long enough to bank the protection seen in trials.

For anyone taking semaglutide or weighing it up, this is a reason to think of it as more than a glucose or weight drug: in trials it meaningfully reduced heart attacks and cardiovascular deaths. It is equally a reason to take tolerability seriously, since the benefit was measured in people who stayed on treatment, and a notable share did not. The findings come from trial populations, so how far they generalise to every user is not something this analysis can settle. Any decision about starting or stopping belongs in a conversation with a prescriber.