Quick answer: retatrutide clinical trials have already produced five phase 3 results, led by TRIUMPH-1, where average weight loss over 80 weeks reached 25.0% on the 12 mg dose versus 3.9% on placebo.[1] Most trials have finished enrolling. As of October 18, 2026, the only Lilly-sponsored retatrutide drug trial listed as recruiting on ClinicalTrials.gov is SYNERGY-OUTCOMES, a liver disease study.[8]
Retatrutide is an investigational once-weekly injection from Eli Lilly and is not FDA-approved. Lilly says it is legally available only to participants in its clinical trials,[2] plus a narrow expanded access program. This page covers what the trials found, which are still running, and how to join one. For the drug itself, see the retatrutide profile.
Phase 3 results so far
The phase 3 TRIUMPH program for obesity enrolled more than 5,800 people across four trials, with all participants also receiving lifestyle counselling on healthy eating and physical activity.[7] A separate program, TRANSCEND, tests retatrutide for type 2 diabetes.
| Trial | Who | Weeks | Main result | Placebo |
|---|---|---|---|---|
| TRIUMPH-1 | 2,339 adults with obesity, no diabetes | 80 | Weight −17.6% to −25.0% | −3.9% |
| TRIUMPH-2 | 1,152 adults with obesity and type 2 diabetes | 80 | Weight −11.9% to −18.8% | −5.1% |
| TRIUMPH-3 | 1,949 adults with severe obesity and heart disease | 80 | Weight −21.6% to −22.6% (if stayed on treatment) | −3.2% |
| TRIUMPH-4 | 445 adults with obesity and knee osteoarthritis | 68 | Weight −20.0% to −23.7% | −4.6% |
| TRANSCEND-T2D-1 | 537 adults with early type 2 diabetes | 40 | HbA1c −1.69 to −1.94 points | −0.81 |
Sources: TRIUMPH-1,[1] TRIUMPH-2,[3] TRIUMPH-3,[4] TRIUMPH-4[5] and TRANSCEND-T2D-1.[6]
A few points stand out:
- Three phase 3 papers so far. TRIUMPH-1, TRIUMPH-2 and TRANSCEND-T2D-1 were published in full in 2026. TRIUMPH-3 and TRIUMPH-4 results come from Lilly press releases and were not in a journal as of our October 2026 PubMed search.[4][5]
- Beyond weight. TRIUMPH-1 also reduced knee pain in 574 participants with knee osteoarthritis and breathing interruptions in 243 with sleep apnea.[1]
- Side effects. The most common were gastrointestinal: nausea, diarrhea, constipation and vomiting. See retatrutide side effects for rates by dose, and retatrutide weight loss results for the full numbers.
Trials still under way
Several large trials have finished enrolling but not yet reported. Each one answers a question the first wave of trials could not.
| Trial | What it tests | People | Main results expected |
|---|---|---|---|
| TRIUMPH-5 | Retatrutide vs tirzepatide | About 800 | November 2026 |
| TRIUMPH-6 | Keeping weight off after 80 weeks | 643 | April 2028 |
| TRIUMPH-7 | Chronic low back pain | 586 | September 2027 |
| TRIUMPH-8 | Weight loss over 56 weeks | 250 | July 2027 |
| TRIUMPH-9 | Different dose-escalation schedules | 600 | October 2028 |
| TRIUMPH-Outcomes | Heart attacks, strokes and kidney decline | About 10,000 | February 2029 |
| TRANSCEND-T2D-2 | Retatrutide vs semaglutide in type 2 diabetes | 1,250 | Main phase completed August 2026 |
Dates are the estimated primary completion dates on each registry record.[9][10][11][12][13][14][15]
TRIUMPH-5 is the trial most people are waiting for, because it is the first direct comparison with an approved drug. Our retatrutide vs tirzepatide comparison will be updated when it reports. TRIUMPH-6 matters for anyone wondering what happens after the dose stops: after 80 weeks on retatrutide, participants are randomized to stay on their dose, change dose or switch to placebo for 36 weeks.[10]
Which retatrutide trials are recruiting now
SYNERGY-OUTCOMES (NCT07165028) is recruiting about 4,500 adults with metabolic dysfunction-associated steatotic liver disease (MASLD), a fatty liver condition, who are at higher risk of serious liver complications. Participants are randomly assigned to retatrutide, tirzepatide or placebo for roughly 224 weeks, and an optional 2-year extension offers active drug to everyone afterward.[8]
Key entry criteria listed on the record include:[8]
- liver fat of 8% or more, with blood and liver-stiffness test results in a range that suggests liver scarring (fibrosis)
- a BMI of 25 or more
- no other type of liver disease, and no past complications of advanced liver disease
- no loss of more than 11 pounds in the 3 months before screening
- HbA1c of 10% or less, and no type 1 diabetes
The record lists 563 sites in 34 countries and territories, including the United States.[8] This is a liver trial, not a weight-loss trial, so most people searching for “retatrutide trials near me” will not qualify.
Lilly-sponsored trials are the ones that test the drug. Some other studies mention retatrutide only because participants may already be taking an incretin medicine; they do not provide it.
How to find and join a trial
- Search ClinicalTrials.gov. Enter “retatrutide” as the intervention, filter by “Recruiting” and add your location. Each record lists the sponsor, eligibility criteria and site contacts.
- Check Lilly’s own trial finder at trials.lilly.com, which lists Lilly-sponsored studies.
- Read the eligibility criteria. These are the “inclusion” and “exclusion” rules that decide who can take part, based on factors such as age, health history and treatment history.[18]
- Contact the site or ask your clinician. The study team screens you, often with blood tests and a medical history.
- Go through informed consent. The team explains the purpose, length, procedures, risks and benefits in writing before you agree. Taking part is voluntary, and you can leave the study at any time.[18]
Common reasons people are excluded
The obesity trials share many exclusion rules. In TRIUMPH-1, for example, people could not join if they had:[16]
- diabetes (TRIUMPH-2 was the trial for people with type 2 diabetes)
- a weight change of more than 5 kg (11 pounds) in the previous 90 days
- taken any weight-loss drug, including over-the-counter products, in the previous 90 days
- had or planned weight-loss surgery
- a personal or family history of medullary thyroid cancer or MEN 2
- a history of pancreatitis
What taking part actually involves
- You may get placebo. Trials are double-blind. TRIUMPH-2 assigned one in four participants to placebo, and TRIUMPH-3 one in two.[3][4] The NIH notes you will be told whether a study uses placebo before you join.[18]
- Doses rise slowly. In phase 3, everyone assigned to retatrutide started at 2 mg weekly and stepped up every four weeks toward 4, 9 or 12 mg.[4][5] See the retatrutide dosage guide.
- It is a long commitment. TRIUMPH-1 lasted about 89 weeks with up to 24 visits.[16]
- Doses can be lowered. Investigators could reduce the dose for persistent stomach side effects, or if a participant’s BMI fell to 22 or below.[7]
If you cannot join a trial
Since June 2026, Lilly has offered single-patient expanded access for adults with a BMI of 35 or more, despite the highest available dose of an approved weight-management drug, plus at least two serious or life-threatening obesity-related complications, who cannot join a trial. A doctor must request it.[17]
Lilly says its data package is complete and plans to submit retatrutide to the FDA in the first quarter of 2027.[20] See when will retatrutide be available? for the timeline.
Questions to ask before you join
- Is this trial placebo-controlled, and what are my chances of getting the study drug?
- How many visits, blood tests and scans are involved, and are travel costs covered?
- What happens to my treatment when the study ends?
- Who do I call about side effects between visits?
- Can I keep taking my current medicines?
