The SELECT trial is one of the most important studies in obesity medicine. Published in the New England Journal of Medicine in November 2023 (Lincoff et al., NEJM 2023;389:2221-2232), this landmark trial showed that semaglutide 2.4 mg (Wegovy) reduces cardiovascular risk in people with obesity — even if they do not have diabetes.
What the SELECT Trial Found
This was a massive study: 17,604 patients across 41 countries, followed for an average of nearly 40 months.
Key eligibility criteria: Age 45+, BMI 27 or higher, established cardiovascular disease (prior heart attack, stroke, or peripheral artery disease), and no history of diabetes.
Primary Results
| Outcome | Semaglutide | Placebo | Risk Reduction |
|---|---|---|---|
| Major adverse cardiovascular events (MACE) | 6.5% | 8.0% | 20% reduction (HR 0.80, p<0.001) |
| Cardiovascular death | 2.5% | 3.0% | 15% reduction (HR 0.85, p=0.07) |
| Nonfatal heart attack | 2.7% | 3.7% | 28% reduction (HR 0.72) |
| Nonfatal stroke | 1.8% | 2.1% | 11% reduction (HR 0.89) |
| All-cause death | 4.3% | 5.2% | 19% reduction (HR 0.81) |
Note: HR = hazard ratio. All values from Lincoff et al., NEJM 2023.
Why This Matters
This was the first trial to demonstrate that a weight loss medication reduces cardiovascular risk independently of diabetes status. Previous weight loss medications (orlistat, phentermine, topiramate) had never shown cardiovascular benefit in a dedicated outcomes trial.
The 20% reduction in MACE is comparable to what statins achieve for secondary prevention. This suggests that GLP-1 medications may become standard of care for cardiovascular prevention in patients with obesity, regardless of whether they need weight loss.
How Does Semaglutide Protect the Heart?
The benefits appear to go beyond weight loss alone. In the SELECT trial, the cardiovascular benefits emerged early — before significant weight loss had occurred. Proposed mechanisms include:
- Anti-inflammatory effects: GLP-1 receptor agonists reduce systemic inflammation, a key driver of atherosclerosis
- Blood pressure reduction: Participants saw systolic BP drop by approximately 3-5 mmHg
- Improved lipid profile: Reductions in non-HDL cholesterol and triglycerides
- Direct vascular effects: GLP-1 receptors are present on vascular endothelium and may have direct protective effects
Side Effects in the Trial
Gastrointestinal side effects were common, consistent with previous GLP-1 studies. Discontinuation due to adverse events occurred in 16.6% of the semaglutide group vs 8.2% in the placebo group. Serious adverse events were similar between groups.
Clinical Implications for 2026
The SELECT trial has changed clinical practice. Cardiologists are now prescribing GLP-1 medications for patients with obesity and cardiovascular disease, even when weight loss is not the primary goal. In 2026, Wegovy carries an FDA-approved label indication for reducing cardiovascular risk in adults with overweight or obesity and established cardiovascular disease.
References:
1. Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. NEJM 2023;389:2221-2232. ClinicalTrials.gov ID: NCT03574597.
2. American College of Cardiology. Semaglutide Effects on Cardiovascular Outcomes in People With Overweight or Obesity — SELECT. ACC.org, Nov 2023.