Eli Lilly reported on 23 July 2026 that retatrutide, an investigational triple hormone receptor agonist, met its primary endpoint in two further Phase 3 trials. Participants with obesity and type 2 diabetes lost up to an average of 20.8% of body weight over 80 weeks; those with severe obesity and established cardiovascular disease lost up to 22.6%. Those are the largest averages yet reported for a weight-loss drug at this stage. The cardiovascular results, in a trial run specifically in cardiovascular patients, are the part worth reading slowly.
What the two trials measured
Retatrutide activates three receptors rather than one: GIP, GLP-1, and glucagon. Approved medicines in this class act on one or two. Both trials ran 80 weeks against placebo.
TRIUMPH-2 enrolled adults with obesity or overweight and type 2 diabetes — a group that reliably loses less weight on these drugs than people without diabetes. From an average baseline of 106.4 kg, the three trial arms lost an average of 12.7%, 19.1% and 20.8% of body weight, against 4.0% on placebo. A1C fell by up to 1.6 percentage points from a baseline of 7.7%.
TRIUMPH-3 enrolled adults with severe obesity and established cardiovascular disease, average baseline 111.4 kg and BMI 40.4. Its two arms lost 21.6% and 22.6%, against 3.2% on placebo. Lilly also reported reductions in triglycerides of 37.0%, non-HDL cholesterol of 16.5%, systolic blood pressure of 9.3 mmHg, and high-sensitivity C-reactive protein of 51.2% at the higher dose.
What the topline does not show
Improving cardiovascular risk factors is not the same as reducing cardiovascular events, and TRIUMPH-3 did not demonstrate the latter. For the broader composite of five event types, the hazard ratio was 0.82 with a 95% confidence interval of 0.55 to 1.22. For the narrower three-event composite it was 1.12, interval 0.64 to 1.96. Both intervals cross 1.0, which means neither result rules out no effect — or, for the narrower measure, a worse one. Lilly noted that events occurred less frequently than anticipated in both arms, which widens the intervals; the trial was not designed to prove a cardiovascular benefit. Read as topline, this is a weight-loss result in a cardiovascular population, not a cardiovascular outcomes result.
Side effects followed the pattern of the drug class and scaled with dose: diarrhoea in up to 33.6% of participants, nausea up to 28.0%, constipation up to 18.0%. Two things stand out. Discontinuation because of adverse events reached 13.5% in the highest TRIUMPH-3 arm against 4.8% on placebo — roughly one participant in seven stopping. And dysesthesia, an altered or burning skin sensation not typical of GLP-1 medicines, appeared in 7.3% of the top TRIUMPH-2 arm against 0.7% on placebo. Lilly describes these events as generally mild to moderate, with most resolving during treatment.
What is not yet known
This is a company topline announcement, not a peer-reviewed paper. Lilly says detailed results will be presented at medical meetings and published later, which is where the full safety tables, dropout accounting and subgroup data will appear. Until then every figure above is the sponsor’s own summary of its own trial, and we have not seen the underlying data.
Retatrutide is not approved and is not available. Lilly says it is completing the manufacturing data package and plans to file for US approval in the first quarter of 2027, which puts any launch well beyond that. Nothing here changes what is available or what it costs today. If retatrutide is eventually approved and priced like its predecessors, the cost question will look much as it does now.
Sources: Eli Lilly news release, 23 July 2026
