SELECT Trial Five-Year Follow-Up: Cardiovascular Outcomes Data

The SELECT trial established semaglutide's cardiovascular benefit in patients with obesity but without diabetes. Here's what the extended follow-up shows after 5 years.

The SELECT trial (Semaglutide Effects on Cardiovascular Outcomes in People With Overweight or Obesity) was the first and largest cardiovascular outcomes trial of a GLP-1 receptor agonist in a population without diabetes but with established cardiovascular disease. Its initial 2023 publication demonstrated that weekly semaglutide 2.4 mg reduced major adverse cardiovascular events (MACE) by approximately 20% compared to placebo. The extended follow-up data released through 2025 and 2026 has strengthened and expanded the original finding.

SELECT is the evidentiary foundation for both the FDA's 2024 cardiovascular risk reduction label for Wegovy and for the expansion of Medicare coverage that followed. Understanding what the trial actually measured — and what the follow-up data now shows — is essential for interpreting the broader GLP-1 cardiovascular story.

Trial Design

SELECT enrolled 17,604 adults aged 45 and older with overweight or obesity (BMI ≥27) and established cardiovascular disease but without type 2 diabetes. Participants were randomized 1:1 to weekly subcutaneous semaglutide 2.4 mg or matching placebo, in addition to standard-of-care cardiovascular prevention. The primary endpoint was a composite of cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke (MACE). Median follow-up at the primary analysis was approximately 40 months.

Primary Results

The 20% MACE reduction was statistically and clinically significant. The number needed to treat over the trial period to prevent one MACE event was approximately 67. For comparison, that is in the range observed for high-intensity statin therapy in similar secondary prevention populations.

Extended Follow-Up Findings

Extended follow-up analyses reported in 2024-2025 have shown that the cardiovascular benefit of semaglutide is maintained with longer exposure and that the hazard curves continue to separate over time. This is important because some anti-obesity therapies have shown diminishing cardiovascular benefit at longer follow-up. Semaglutide's benefit has proven durable, and the MACE reduction has persisted in subgroup analyses across age, baseline BMI, baseline LDL cholesterol, and prior MI history.

Secondary and Exploratory Endpoints

Beyond the primary MACE composite, SELECT has generated a rich set of secondary analyses. Heart failure events were reduced, consistent with the subsequent STEP HFpEF trial findings. Atrial fibrillation incidence showed a possible reduction signal. Hospitalization for cardiovascular causes was reduced. Weight loss was maintained across the trial period (approximately 9.4% mean reduction from baseline).

Importantly, the cardiovascular benefit does not appear to be explained entirely by weight loss. Statistical analyses examining the relationship between degree of weight loss and MACE reduction have consistently shown that the cardiovascular protection is only partially mediated by weight change — suggesting direct pharmacologic effects on cardiovascular biology beyond the indirect weight-loss pathway.

Safety Profile

Serious adverse events were slightly more common in the placebo arm than the semaglutide arm, driven by cardiovascular event differences. Gastrointestinal adverse events (nausea, vomiting, diarrhea) were substantially more common with semaglutide, as expected from the STEP and SUSTAIN programs. Cholelithiasis was modestly increased. No increased signal for pancreatic cancer, thyroid cancer, or major depression emerged with extended follow-up.

What SELECT Established

The trial's impact on the clinical landscape has been substantial. The FDA approved a cardiovascular risk reduction indication for Wegovy in 2024 based on SELECT. CMS used the finding as part of the justification for expanded Medicare coverage. Major cardiology society guidelines now include GLP-1 receptor agonists as a class-level consideration for secondary prevention in appropriate patients.

Open Questions

SELECT was a single trial in a specific population. Questions that remain open include whether the benefit extends to primary prevention (patients without established cardiovascular disease), whether similar benefits accrue to tirzepatide (addressed in part by SURPASS-CVOT), whether oral semaglutide provides comparable cardiovascular protection, and how the cardiovascular benefit evolves over 5+ year exposure. Several of these questions are being addressed in ongoing trials. For related coverage, see our SURPASS-CVOT review and STEP HFpEF review.

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