Semaglutide's trial record spans two major named programs, STEP and SELECT, that together illustrate how a drug's evidence base can expand well beyond its original approved use through continued rigorous trial work.

The STEP Program

The STEP trials were specifically designed to evaluate semaglutide for chronic weight management, enrolling participants with obesity or overweight, and reporting substantial average weight loss compared to placebo over roughly 68 weeks across the program's several trials, which included different participant populations and trial designs. This program directly supported the drug's approval as Wegovy.

The SELECT Trial

The SELECT trial took a different approach, enrolling participants with established cardiovascular disease and overweight or obesity, but without diabetes, and evaluated whether semaglutide reduced major adverse cardiovascular events, heart attack, stroke, and cardiovascular death, over an extended follow-up period. The trial reported a statistically significant reduction in this composite outcome, a finding with significant clinical implications well beyond weight loss alone.

Why the SELECT Trial Mattered So Much

This result was significant partly because it demonstrated a hard clinical outcome, actual reduction in serious cardiovascular events, rather than a surrogate marker like weight or blood sugar alone. It also helped support broader conversations, including with insurers, about semaglutide's value beyond weight loss specifically, since cardiovascular event reduction is a more directly meaningful outcome in the way clinical medicine and insurance coverage decisions are typically evaluated.

Trial Scale

Both programs involved large participant numbers, the SELECT trial alone enrolled over 17,000 participants, a scale that provides considerably more statistical confidence than the small studies common for unapproved peptides discussed elsewhere on this site, and that's specifically capable of detecting relatively rare but serious outcomes that smaller trials simply aren't powered to catch.

The Bottom Line

Between STEP and SELECT, semaglutide has one of the most extensive trial records of any drug discussed on this site, spanning multiple distinct outcomes and tens of thousands of participants, which is a big part of why it's held up as a reference point for what a well-established peptide drug's evidence base actually looks like.

Why Regulators and Insurers Both Paid Close Attention to SELECT

The SELECT trial's cardiovascular findings mattered beyond the immediate clinical community, since a demonstrated reduction in heart attacks and strokes is exactly the kind of hard outcome that influences both regulatory labeling decisions and insurance coverage policy discussed elsewhere on this site, a different and in some ways higher bar than a weight-loss or blood-sugar endpoint alone, and part of why this trial specifically continues to come up in policy discussions well beyond semaglutide's original approved indications.