SURPASS-CVOT completes after more than four years of follow-up

SURPASS-CVOT, the biggest and longest trial of tirzepatide (sold as Mounjaro for type 2 diabetes and Zepbound for obesity and sleep apnea), reached its listed study completion date of June 12, 2025. The trial randomized 13,299 participants at 640 sites across 30 countries, according to its registry record ^[1].

What sets the trial apart is its comparison group. Most cardiovascular outcomes trials for diabetes drugs test the new medicine against a placebo added to usual care. SURPASS-CVOT instead compared tirzepatide head-to-head against dulaglutide 1.5 mg, an older once-weekly GLP-1 receptor agonist that already carries evidence from its own cardiovascular outcomes program ^[1].

An active comparator changes the question

A placebo-controlled trial asks whether a drug lowers cardiovascular risk compared with no added therapy. An active-comparator trial asks a harder question: whether the newer drug does at least as well as, or better than, a drug already shown to be useful. That design choice affects how results get interpreted. A finding of non-inferiority would mean tirzepatide is not meaningfully worse than dulaglutide on the outcomes measured. A finding of superiority would mean it did better. The trial's registry entry lists dulaglutide 1.5 mg as the comparator, but the specific statistical margins and the full outcome definitions are not detailed in what has been posted publicly here ^[1].

The scale is worth noting. With 13,299 people randomized and follow-up spanning more than four years, the trial accumulated a large amount of person-time — the kind of exposure needed to detect differences in relatively uncommon events like heart attack, stroke and cardiovascular death, and to pick up safety signals that shorter trials can miss ^[1].

The 640 sites in 30 countries also mean the population was geographically broad. How that translates to US patients specifically — including the racial, ethnic and age makeup of enrollees — has not been detailed in the information posted to the registry record.

What is not yet known

As of the completion date, results had not been posted. The registry record does not include outcome data, and no topline numbers have been disclosed through it ^[1]. Under US law, sponsors generally have up to one year after a trial's primary completion date to submit results to ClinicalTrials.gov, though sponsors can file a certification to delay results submission for up to two years if they are seeking FDA approval for a new drug or a new use of an already approved drug ^[1].

That means the gap between a completion date and public results can be substantial. Trial sponsors also frequently release topline findings through press announcements and present full data at medical conferences before the registry record is updated.

Why it matters for patients

For people taking or considering tirzepatide, cardiovascular outcomes data answers a practical question: beyond blood sugar and weight, does the drug affect the risk of heart attacks, strokes and cardiovascular death? Semaglutide already carries cardiovascular indications based on its own outcomes trials. Tirzepatide's labeling and how clinicians and insurers weigh it against other options could shift depending on what SURPASS-CVOT shows.

The active-comparator design adds nuance. Because the control group received an active GLP-1 drug rather than placebo, the trial cannot directly show how tirzepatide compares with no GLP-1 treatment at all. It can speak to how tirzepatide stacks up against an established option in the same class ^[1].

What happens next

The completion date of June 12, 2025 starts the clock on results reporting ^[1]. Whether the sponsor releases topline findings first through a public announcement, and the timing of any conference presentation or peer-reviewed publication, has not been announced.