Retatrutide: What the Evidence Actually Shows

As of August 2026, a ClinicalTrials.gov intervention search for retatrutide returns 33 registered studies: 14 phase 3, 4 phase 2, 14 phase 1, and one expanded-access record. Of the 14 phase 3 records, none has posted results in the registry's own results database; the two studies in the whole set that have are both phase 2, NCT04881760 and NCT04867785. Results posting and journal publication are separate things, and retatrutide is currently a case where they disagree: TRANSCEND-T2D-1 (NCT06354660) is published in a journal and has no registry results posted. Five of the 14 phase 3 records are listed as completed; the other nine are still running, including a 10,000-participant cardiovascular and kidney outcomes trial with a listed completion date of February 2029.

The four registrational TRIUMPH trials enrolled 5,878 participants between them, and all four have now finished: TRIUMPH-4 on November 14, 2025 (445 participants), TRIUMPH-1 on April 30, 2026 (2,335), TRIUMPH-3 on May 14, 2026 (1,946), and TRIUMPH-2 on June 16, 2026 (1,152) ⁴. None has posted results on ClinicalTrials.gov or appeared in a journal as of August 2026. They are also not four identical reads on the same question: TRIUMPH-2 enrolled people with type 2 diabetes, TRIUMPH-3 people with obesity and established cardiovascular disease, and TRIUMPH-4 people with knee osteoarthritis, with WOMAC pain or a sleep-apnea endpoint layered on top of body weight in three of the four ⁴. Only TRIUMPH-3 has percent weight change as its sole primary endpoint.

TRANSCEND-T2D-1 is the retatrutide phase 3 trial with published results, and it is worth being exact about its scope. It gave retatrutide as a monotherapy to adults whose type 2 diabetes was inadequately controlled by diet and exercise alone, for 40 weeks, with change in HbA1c as the primary endpoint. It established that all three doses lowered HbA1c more than placebo and that weight fell 15.3% on 12 mg against 2.6% ³.

It does not establish four things people read into it. It is not an obesity result — its stated eligibility criteria were type 2 diabetes inadequately controlled by diet and exercise alone, an HbA1c between 7.0% and 9.5%, and a BMI of at least 23, and the enrolled group's mean baseline HbA1c was 7.9% ³. It is not a durability result: 40 weeks is shorter than the 48 weeks of the phase 2 obesity trial ¹. It is not a safety record — two deaths occurred, both in the 4 mg group and both judged unrelated to the study drug, in a trial of 537 people over 40 weeks, which is not the scale at which rare harms become visible ³. And it is not an approval, or evidence of one coming.

It is also not a downgrade of the 24.2%. The two figures differ on population, on duration, and on estimand — TRANSCEND-T2D-1 states its numbers are the treatment regimen estimand, which keeps a participant's data in the analysis after they stop the study drug ³, where the phase 2 obesity trial reports a least-squares mean without naming an estimand ¹. When three things move at once, the difference between the two numbers cannot be assigned to any of them. Our weight loss evidence page lines this compound up against the approved options rather than against its own earlier trial.

TRIUMPH-5 (NCT06662383) is putting retatrutide directly against tirzepatide in an estimated 800 adults with obesity, listed as active and not recruiting, with an estimated completion of December 2026. Until it reads out, a "retatrutide beats tirzepatide" claim is two separate trials' numbers set side by side, not a head-to-head result — three receptors versus two is arithmetic, not evidence.

At 48 weeks on 12 mg, 100% of participants lost at least 5% of body weight, 93% lost at least 10%, and 83% lost at least 15%; on placebo those figures were 27%, 9%, and 2% ¹. That is the honest version of a before-and-after. What it cannot show is what the person in any given online photo actually injected — there is no approved product to dispense, and the only ways to receive retatrutide from its manufacturer are enrolling in one of the trials still recruiting or the single-patient expanded-access program (NCT07629401), which is physician-requested for narrowly defined cases. Neither is a commercial channel.

This is our reading of the rules, not a finding from a cited study. Compounded semaglutide and tirzepatide markets exist because those are FDA-approved drugs that entered a declared shortage — the circumstance that opens a Section 503A compounding route. Retatrutide has no FDA approval, so that route does not open for it, and material sold under the name is not a compounded prescription, whatever the seller calls it.

Two federal databases get pointed at as proof retatrutide is a recognized product, and both collapse the same way on inspection. DailyMed returns ten retatrutide labels, all ten submitted by one cross-border e-commerce company — DailyMed publishes what registrants file about themselves, not an FDA review. The NDC Directory returns twelve retatrutide records across seven labelers, every one categorized as bulk ingredient, and none carrying the application number an approved medicine is sold under. Both are the paperwork of a chemical supply chain, not a drug approval.