Ask most people what a GLP-1 does and they'll say weight loss or blood sugar. Several of these drugs have also been put through dedicated cardiovascular outcomes trials, large studies built to answer one question: do fewer people on the drug have a heart attack, a stroke, or die of cardiovascular causes? For liraglutide and semaglutide, the answer was yes.
More than a weight-loss or diabetes drug
That's a stronger kind of evidence than "weight loss is generally good for your heart." The trials counted actual events, not just changes in blood pressure or cholesterol, and you can see how they fit alongside the rest of the research in our large-scale clinical trial evidence guide. How much of the benefit comes from weight loss is still an open question. In SELECT, the heart benefit showed up at every starting weight and didn't track closely with how much weight people lost, which points to some effect beyond fat loss (more on that below).
The landmark trials
LEADER (liraglutide). This trial randomized 9,340 patients with type 2 diabetes and high cardiovascular risk to liraglutide or placebo. Liraglutide significantly reduced the primary composite outcome of cardiovascular death, non-fatal heart attack, or non-fatal stroke (13.0% vs. 14.9% with placebo). It also reduced cardiovascular death on its own (4.7% vs. 6.0%) and death from any cause (8.2% vs. 9.6%) over a median follow-up of 3.8 years (Marso et al., New England Journal of Medicine, 2016, DOI (external link)). It was one of the first trials to show that a GLP-1 medication could cut cardiovascular events, and not only improve risk factors like blood sugar.
SELECT (semaglutide). SELECT asked whether the benefit held for people with overweight or obesity and established cardiovascular disease but no diabetes. It did: semaglutide reduced major adverse cardiovascular events by 20% compared with placebo (Lincoff et al., New England Journal of Medicine, 2023, DOI (external link)). A related substudy found semaglutide also slowed kidney decline, with a lower rate of significant loss of kidney function and kidney disease progression (Colhoun et al., Nature Medicine, 2024, DOI (external link)). A prespecified SELECT analysis then looked at weight. The benefit was consistent across all starting weights and waist sizes, weight loss at week 20 didn't predict who later had fewer events, and an estimated 33% of the benefit was explained by a smaller waist. The authors read that as a sign that some of the protection comes from mechanisms beyond losing fat (Deanfield et al., The Lancet, 2025, DOI (external link)).
FLOW (semaglutide, kidney disease). FLOW tested the kidney signal directly. It randomized 3,533 patients with type 2 diabetes and chronic kidney disease to semaglutide 1.0 mg or placebo and was stopped early for efficacy. Over a median 3.4 years, major kidney disease events were 24% lower with semaglutide, cardiovascular death was 29% lower, and death from any cause was 20% lower (Perkovic et al., New England Journal of Medicine, 2024, DOI (external link)).
STEP-HFpEF (semaglutide, heart failure). In patients with obesity and a specific type of heart failure (heart failure with preserved ejection fraction, or HFpEF), semaglutide improved heart failure symptoms, physical function, and exercise capacity, along with weight loss (Kosiborod et al., New England Journal of Medicine, 2023, DOI (external link)).
SURPASS-CVOT (tirzepatide). Tirzepatide's cardiovascular trial had no placebo arm. It compared tirzepatide head-to-head with dulaglutide, a GLP-1 already proven to reduce cardiovascular events. In 13,299 patients with type 2 diabetes and established cardiovascular disease, tirzepatide was non-inferior to dulaglutide on cardiovascular death, heart attack, or stroke (12.2% vs. 13.1%; hazard ratio 0.92) and narrowly missed statistical superiority (Nicholls et al., New England Journal of Medicine, 2025, DOI (external link)). Put simply, tirzepatide protects at least as well as a GLP-1 with proven heart benefit, but it hasn't been shown to protect more. Based on this trial, the FDA approved Mounjaro (tirzepatide) on August 28, 2026 to reduce the risk of cardiovascular death, non-fatal heart attack, or non-fatal stroke in adults with type 2 diabetes at high risk of these events (status as of September 2026; Lilly announcement (external link)).
Class-wide evidence. A 2025 meta-analysis pooled 21 randomized controlled trials, 99,599 patients and eight GLP-1 medications. Compared with placebo or other controls, the class reduced death from any cause by 12%, cardiovascular death by 13%, and major adverse cardiovascular events by 13%, with 15% reductions in both heart attacks and heart failure. The authors rated the evidence as conclusive and high-certainty. Stroke was the exception: the pooled data showed no clear difference (Galli et al., Journal of the American College of Cardiology, 2025, DOI (external link)). So the benefit looks like a class effect across several drugs, and it shows up mainly as fewer heart attacks, fewer heart failure events and fewer cardiovascular deaths.
Why these medications appear to help the heart
Researchers are still working out the mechanisms. The contributors usually discussed, which can all be true at once:
- Weight loss itself lowers the strain on the heart and improves risk factors such as blood pressure, cholesterol and blood sugar.
- GLP-1 receptors sit in cardiovascular tissue, and there's evidence these drugs may calm inflammation and act on blood vessels directly, apart from weight loss.
- Blood pressure and lipid profiles tend to improve on GLP-1 treatment, beyond the headline weight and blood sugar numbers.
- The heart and kidneys share a lot of disease biology, so easing strain on one can help the other, which fits the kidney benefit seen in SELECT.
Important context and caveats
- The strongest evidence is in people who already have cardiovascular disease or major risk factors. LEADER and SELECT both enrolled people with diabetes or established cardiovascular disease. That doesn't rule out benefit for lower-risk people, but the trials didn't test them directly.
- Results aren't identical across every GLP-1 or dose. Each outcomes trial used a specific drug, dose and population. Don't assume the results carry over unchanged to every GLP-1 on the market, especially newer drugs that haven't finished a cardiovascular outcomes trial.
- Real-world results can differ from trial results. A 2025 review found that weight loss and adherence with GLP-1 medications tend to be lower in everyday use than in controlled trials, with many people stopping in the first year. Trial-level heart benefits are most likely with steady, long-term use (Thomsen et al., Diabetes, Obesity & Metabolism, 2025, DOI (external link)).
- The benefits come with known risks. The same trials recorded the class's real adverse effects. See our guides on gallbladder disease and gallstones on a GLP-1 and kidney injury risk from dehydration. The heart case is something to weigh, not a free pass.
- A GLP-1 doesn't replace your other heart care. Blood pressure medication, statins and other established treatments still matter, alongside GLP-1 therapy where appropriate.
Study findings above are attributed to their authors and were located via PubMed.
This is general education and peer information, not medical advice. Decisions about your cardiovascular care and treatment belong with your prescriber.