GLP-1 Drugs and Cardiovascular Risk: What the SELECT Trial Found in Non-Diabetic Patients

Before the SELECT trial, GLP-1 drugs had solid cardiovascular outcome data in people with type 2 diabetes, but not in people who had obesity and cardiovascular disease without diabetes — a genuinely different population that SELECT was specifically designed to test.

Why This Population Mattered

Earlier cardiovascular outcome trials for GLP-1 drugs, which supported claims of cardiovascular benefit in diabetes, enrolled diabetic populations specifically — leaving open the question of whether the cardiovascular benefit came from the drug's effect on cardiovascular risk directly, or was somehow tied to its glucose-lowering effect in people who already had diabetes. SELECT, published in 2023, enrolled over 17,000 adults with established cardiovascular disease and overweight or obesity, but explicitly without diabetes, specifically to isolate whether the cardiovascular benefit held in a non-diabetic population.

What SELECT Found

SELECT found semaglutide reduced the risk of major adverse cardiovascular events, a composite of cardiovascular death, non-fatal heart attack, and non-fatal stroke, by a statistically significant margin compared to placebo over roughly three years of follow-up — in a population without diabetes. This was the first large randomized trial to demonstrate a GLP-1 drug's cardiovascular benefit independent of a diabetes diagnosis, which meaningfully expanded how these drugs are understood: not simply as diabetes or weight-loss drugs with a secondary cardiovascular benefit tied to blood sugar control, but as having a cardiovascular-protective effect in a broader population defined by obesity and existing cardiovascular disease.

What This Led To

SELECT's results supported an expanded FDA indication for semaglutide (Wegovy) specifically for reducing cardiovascular risk in adults with established cardiovascular disease and obesity or overweight, separate from its original weight-management indication — a genuinely new, outcome-based approval built on this trial's data, not just an extension of the weight-loss claim.

What SELECT Doesn't Establish

SELECT enrolled a specific population: people with both obesity/overweight and pre-existing cardiovascular disease. It doesn't directly establish the same magnitude of cardiovascular benefit in people with obesity but without existing cardiovascular disease, or in normal-weight individuals — the trial's population defines the population its findings most directly apply to, a common and important caveat across all outcome trials, not unique to SELECT specifically.

How This Complements TRAVERSE and FLOW

SELECT sits alongside TRAVERSE (TRT's cardiovascular safety trial) and FLOW (semaglutide's kidney-outcomes trial) as part of a broader pattern of large, dedicated outcomes trials that have meaningfully upgraded the evidence quality behind these drug classes over the past few years — moving discussion in this space from extrapolated or observational data toward genuine randomized outcome trial evidence on hard clinical endpoints.

Practical Takeaway

SELECT established that semaglutide reduces major cardiovascular events specifically in people with obesity and existing cardiovascular disease, independent of a diabetes diagnosis — a genuinely new, robustly tested finding that expanded the drug's evidence-backed role beyond weight loss and diabetes management. Like any outcome trial, its findings apply most directly to the population it studied, which is worth keeping in mind when generalizing its results.