Retatrutide Clinical Trials (TRIUMPH) Explained

Last updated 13 June 2026

Quick answer

Retatrutide is in Phase 3 trials run by Eli Lilly. An early Phase 2 study (NEJM, 2023) showed up to 17.5% weight loss at 24 weeks. Phase 3 trials called TRIUMPH (for obesity) and TRANSCEND-T2D (for type 2 diabetes) reported strong results in 2025 and 2026. It is not yet approved anywhere.

How drug trials work (quick version)

New treatments are tested in phases. Phase 1 checks basic safety in a few people. Phase 2 tests if it works and finds a dose. Phase 3 is the big test in many people. Only after Phase 3 can a company ask a regulator to approve it.

Phase 2 (2023): the first big result

The Phase 2 results were published in the New England Journal of Medicine in 2023. Adults with obesity or overweight lost up to 17.5% of their body weight over 24 weeks. That number turned a lot of heads, because it was higher than older one- and two-signal peptides.

Phase 3: the TRIUMPH and TRANSCEND trials

Eli Lilly then ran a large set of Phase 3 trials:

TRIUMPH-4 (December 2025) — obesity plus knee osteoarthritis pain. People lost up to an average of about 71 lb (around 32 kg) and had less joint pain.
TRIUMPH-1 (2026) — obesity with at least one weight-related health problem, with smaller "basket" sub-studies in knee pain and sleep apnea.
TRANSCEND-T2D-1 (2026) — type 2 diabetes. It lowered both A1C (a blood sugar marker) and weight. Full results were published in The Lancet in June 2026.

More trials are still running, including studies in sleep apnea, heart disease, kidney disease, and liver disease.

What this means

The science behind retatrutide is strong and growing. But "strong trial results" is not the same as "approved medicine". Until a regulator signs off, it stays a research compound. See our UK legal status page.

Strong trial results are why so many UK researchers want to buy retatrutide UK. Just make sure any supplier is COA-verified first.

Looking at suppliers?

See where UK researchers source retatrutide

Common questions

What phase is retatrutide in?+

Retatrutide is in Phase 3, the final stage before a company can ask regulators to approve a medicine. As of 2026 it has completed several Phase 3 trials, with more still running.

What is the TRIUMPH programme?+

TRIUMPH is the name of Eli Lilly's group of Phase 3 trials for retatrutide in obesity. TRANSCEND-T2D is the matching group of trials for type 2 diabetes.

Is retatrutide approved yet?+

No. Even after positive Phase 3 results, a regulator still has to review and approve it. That had not happened anywhere as of 2026.