The SELECT trial semaglutide results showed fewer serious heart and blood-vessel events: about 65 in every 1,000 people given semaglutide had an event, compared with 80 in every 1,000 given placebo, a look-alike shot without the drug. That was over roughly 40 months. The often-quoted 20% describes a relative reduction over time, not 20 fewer events per 100 people.
The participants already had cardiovascular disease, meaning disease of the heart or blood vessels. They had overweight or obesity, but no diabetes. That combination matters when deciding whom these results describe.
What question did SELECT ask, and who took part?
Could adding semaglutide to usual heart care reduce serious events in people without diabetes? The study enrolled 17,604 adults aged 45 or older with a BMI of at least 27. BMI, or body mass index, relates weight to height. Everyone had a previous heart attack, stroke, or symptomatic peripheral artery disease, meaning narrowed arteries outside the heart, often in the legs.
The average age was about 62. People with diabetes, the most severe heart failure, or kidney failure were excluded, as were people receiving dialysis, a treatment that filters the blood. The SELECT registry record, NCT03574597, identifies the study and its two treatment groups; the 2023 NEJM paper by Lincoff and colleagues reports the results.
People were assigned by chance to weekly semaglutide injections with a target dose of 2.4 mg or placebo. Neither participants nor their treating teams knew the assignment. Both groups continued ordinary heart care, including management of blood pressure and cholesterol. Average follow-up was 39.8 months, though average time receiving the assigned treatment was shorter, at 34.2 months.
What did the researchers count?
The primary endpoint, the main outcome chosen before the trial began, was the first cardiovascular death, nonfatal heart attack, or nonfatal stroke. This three-part measure is called MACE, short for major adverse cardiovascular events.
Counting the first event gives each person one place in the main comparison. It does not count every later hospital visit or repeated event. The analysis also kept people in their originally assigned group even if they stopped treatment, making it a more practical test than counting only people who stayed on the shot.
These were results for the branded study medicine. SELECT did not test a compounded preparation.
SELECT trial semaglutide results: what 20% means
The main result was 6.5% with semaglutide versus 8.0% with placebo: 569 of 8,803 people versus 701 of 8,801. The hazard ratio, a comparison of how quickly events occurred during follow-up, was 0.80. That is where the 20% headline comes from.
The absolute difference was 1.5 percentage points, or roughly 15 fewer people with an event per 1,000 over the study. The two descriptions answer different questions; neither is a personal prediction.
The paper's other outcome measures need more care:
| Outcome during SELECT | Semaglutide | Placebo |
|---|---|---|
| Death from cardiovascular causes | 2.5% | 3.0% |
| Cardiovascular death or a hospital/urgent visit for heart failure | 3.4% | 4.1% |
| Death from any cause | 4.3% | 5.2% |
Heart failure means the heart cannot fill or pump well enough for the body's needs. Cardiovascular death alone did not meet the trial's statistical threshold. Under its preplanned testing order, the next two results therefore remained suggestive rather than confirmed benefits.
The lines tracking events in each group began separating early. At 104 weeks, average weight loss was about 9.4% versus 0.9%. A later SELECT weight analysis, Nature Medicine 2024, reported 10.2% versus 1.5% at four years. Those are group averages at different time points.
Side effects: how many people stopped?
About one person in six assigned semaglutide stopped because of an adverse event, meaning a health problem reported during treatment. Stomach and bowel problems accounted for much of the difference.
These selected rows come from the original safety table, also examined in Kushner and colleagues' SELECT safety analysis, Obesity 2025:
| Reported safety outcome | Semaglutide | Placebo |
|---|---|---|
| Any serious adverse event | 33.4% | 36.4% |
| Permanently stopped treatment because of an adverse event | 16.6% | 8.2% |
| Stopped because of stomach or bowel problems | 10.0% | 2.0% |
| Gallbladder-related problems | 2.8% | 2.3% |
The 10% figure is a stopping rate, not the share who ever felt nauseated. SELECT did not systematically collect every mild symptom. Serious health events were less common overall with semaglutide, while difficulty tolerating treatment was more common.
Tirzepatide is another prescription medicine considered for weight management, but SELECT did not compare it with semaglutide. This trial cannot rank the two for heart outcomes.
What later analyses clarified
One fair question was whether the heart result simply reflected weight loss. In Deanfield and colleagues' Lancet analysis, published in 2025, greater weight loss at week 20 did not show a straight-line relationship with fewer later major events. Researchers estimated that waist reduction explained part of the association. The finding supports looking beyond the scale. But participants were not assigned how much weight to lose, so this analysis cannot prove that weight loss plays no part.
As of September 10, 2026, the day this article was written, a SELECT inflammation analysis published August 18, 2026, in Circulation adds another clue from the same trial. Researchers measured hsCRP, a blood marker of inflammation, and found reductions as early as weeks 4 and 8, including among people without weight loss. Their analysis suggests lower inflammation may explain part of the cardiovascular result; a changing blood marker does not prove how the drug produced it. A mediation analysis published September 23, 2026 found that semaglutide improved every tested mediator, including blood pressure; all mediators combined accounted for an estimated 31.4% of the cardiovascular effect, and none alone or together explained the major-event reduction with certainty (Colhoun et al., European Heart Journal).
The original authors also flagged limited representation of women and Black participants. And because everyone entered with existing artery disease, SELECT cannot establish prevention in otherwise low-risk adults.
What changed for patients, and what did not?
On March 8, 2024, the FDA added a cardiovascular indication to Wegovy injection. An indication is a specific use on a medicine's label. This one covers reducing cardiovascular death, heart attack, and stroke risk in adults with cardiovascular disease and overweight or obesity.
SELECT tested branded Wegovy 2.4 mg. Through Promise, semaglutide is dispensed as a compounded medication, which is different from an FDA-approved product: the formulation offered here is not FDA-approved. Compounding means a pharmacy prepares a medication for a prescription. The FDA explains that it does not review compounded drugs for safety, effectiveness, or quality before sale. SELECT does not establish the same cardiovascular outcomes for that preparation.
A licensed provider may still prescribe a compounded formulation; that decision is between the patient and the doctor.
How this fits a prescribing conversation
The useful questions are whether the person resembles the trial population, which product is being considered, and how treatment fits existing heart care. Promise's semaglutide and heart health guide covers the broader evidence; semaglutide for heart failure explains that separate treatment question.
At Promise, a licensed U.S. provider reviews every request, and not everyone qualifies. The prescriber sets the actual dose. SELECT supplies evidence for that conversation; the person's history, current medicines, and ability to tolerate treatment still decide how it applies.
