TRIUMPH-2: What the Diabetes-Plus-Obesity Trial Adds to the Retatrutide Picture
If you have type 2 diabetes and obesity, and you’ve been following the retatrutide pipeline for the trial that actually applies to you, the answer is TRIUMPH-2. It’s the larger and longer of the two Phase 3 retatrutide trials in adults with type 2 diabetes — the one most likely to anchor a future U.S. label that covers both conditions at once. As of May 2026 it has not yet reported, and this post explains what the trial is and what readout signals will matter most.
TRIUMPH-2 is a randomized, double-blind, placebo-controlled Phase 3 trial of retatrutide in adults with both type 2 diabetes and obesity (or overweight with weight-related comorbidities). It is registered as ClinicalTrials.gov NCT05929079 and is part of Eli Lilly’s TRIUMPH program. The trial is designed to test both glycemic control (A1C) and weight loss as efficacy outcomes, with a planned enrollment of approximately 1,000 participants and an extended treatment duration. Results are expected later in 2026.
TRIUMPH-2 is distinct from TRANSCEND-T2D-1, the smaller diabetes-only Phase 3 trial that reported topline results in March 2026. Where TRANSCEND-T2D-1 established the existence and approximate magnitude of retatrutide’s diabetes effect, TRIUMPH-2 is the trial most likely to be cited in a U.S. label, used for payer negotiations, and compared head-to-head with tirzepatide’s SURPASS data. It is the trial that will materially change what a future retatrutide prescription looks like for someone managing both conditions.
What TRIUMPH-2 Is Designed to Test
TRIUMPH-2 enrolls adults with type 2 diabetes who also have obesity or overweight with at least one weight-related comorbidity. Participants are randomized to retatrutide or matching placebo, in conjunction with a healthy diet and increased physical activity. The trial follows the same general design template as TRIUMPH-1 — randomization, double-blinding, placebo control — but the target population is different in clinically important ways.
Two endpoints anchor TRIUMPH-2: change in A1C and change in body weight. That dual structure matters because it lets the trial generate evidence for two label claims at once: improved glycemic control in type 2 diabetes, and chronic weight management in adults with obesity. A subset of participants with obstructive sleep apnea is also being tracked separately within the trial, paralleling the TRIUMPH-1 sub-cohort design.
For the broader picture of how TRIUMPH-2 fits with the rest of the Phase 3 program, see our TRIUMPH program research summary.
Why a Diabetes-Plus-Obesity Population Matters
Roughly 80% of adults with type 2 diabetes are also living with overweight or obesity. Most existing diabetes guidelines recommend weight loss as a foundational element of diabetes management, but until the GLP-1 era, very few diabetes drugs produced clinically meaningful weight loss as a side effect of treatment. The drugs that do — tirzepatide, semaglutide — became standard-of-care for many patients precisely because of that dual effect.
TRIUMPH-2 is positioned to extend that trajectory. If retatrutide produces both meaningful A1C reduction and meaningful weight loss in the same population in the same trial, the result becomes the obvious comparator for tirzepatide in clinical decision-making for adults with both conditions.
The implication for individual patients is concrete. Many people currently on a diabetes drug for glucose control and a separate weight-management drug for obesity may, after retatrutide approval, end up on a single weekly injection that addresses both. TRIUMPH-2 is the trial that has to prove that combination works.
The Benchmarks Going In
TRANSCEND-T2D-1 set the floor. In that 537-participant 40-week trial, retatrutide reduced A1C by 1.7 to 2.0 percentage points across doses (vs. 0.8 on placebo) and produced a mean 16.8% body-weight reduction at the 12 mg dose. For a longer, larger trial in a similar population, those numbers represent the lower bound of what TRIUMPH-2 needs to confirm.
Tirzepatide’s SURPASS program — the comparator everyone will reach for — reported A1C reductions in the 2.0 to 2.4 percentage point range in similar populations over similar durations, with weight reductions of 7% to 12% in T2D-only populations and somewhat higher in T2D-plus-obesity subgroups. TRIUMPH-2 will be informally — though not formally — read against those numbers.
A clean TRIUMPH-2 readout in roughly that range, with no new safety signals, sets up retatrutide as a credible alternative to tirzepatide in adults with both conditions. A weaker readout would change the conversation about positioning. For more on how the two drugs compare today, see our retatrutide vs tirzepatide overview.
What Will Determine a Successful Readout
Three signals will tell you most of what you need to know on the day TRIUMPH-2’s topline lands.
A1C reduction at the highest dose, placebo-adjusted, in the 1.4 to 2.0 percentage point range or better is the band that lines up with the existing GLP-1 alternatives. Below that, retatrutide loses some of its differentiation argument in T2D specifically.
Body-weight reduction at the highest dose, placebo-adjusted, of 12% or more would extend the TRANSCEND-T2D-1 trajectory and exceed what any approved drug has produced in a comparable T2D population over a comparable duration.
Adverse-event-related discontinuation rate in line with what TRANSCEND-T2D-1 (2.2 to 5.1%) and TRIUMPH-4 reported. A meaningful uptick here — particularly into double digits at the highest dose — would change how clinicians weigh the benefit-risk picture, even if efficacy is otherwise strong.
What TRIUMPH-2 Won’t Resolve
TRIUMPH-2 is placebo-controlled, not active-comparator. It does not produce a head-to-head answer about retatrutide vs tirzepatide in T2D. That data will come from TRIUMPH-5, an active-comparator trial that runs separately. Cross-trial comparisons against tirzepatide remain unreliable.
It also will not, on its own, deliver a U.S. label. The U.S. label for retatrutide will reflect both TRIUMPH-1 (obesity without T2D) and TRIUMPH-2 (T2D plus obesity), along with supportive data from TRIUMPH-4 and the TRANSCEND program.
And it will not answer questions about long-term cardiovascular outcomes, kidney protection, or other organ-specific effects. Those are tracked in the dedicated cardiovascular outcomes trial in the program (TRIUMPH-3) and in the broader TRANSCEND program.
How TRIUMPH-2 Connects to Approval Timing
Eli Lilly has indicated plans to submit a New Drug Application for retatrutide in 2026, anchored by TRIUMPH-1 and TRIUMPH-2 data. A clean TRIUMPH-2 readout in line with TRANSCEND-T2D-1 is one of the conditions for that submission proceeding on the disclosed timeline. A weaker readout, or a new safety signal, would likely trigger Lilly to wait for additional data before filing.
Once a New Drug Application is filed, the FDA’s standard review process applies. Priority review and breakthrough designation can compress that timeline; standard review extends it. The path from successful TRIUMPH-2 readout to U.S. availability is therefore measured in quarters, not weeks.
For the latest publicly known status of retatrutide’s regulatory progress, see our retatrutide approval updates page and the FDA approval status overview.
What to Watch For When the Press Release Drops
When TRIUMPH-2 reports, the Eli Lilly press release will lead with the headline A1C and weight-loss numbers in the highest-dose arm. The more informative numbers usually appear in the second or third paragraph: the placebo-adjusted figures, the responder rates at specific A1C and weight-loss thresholds, and the breakdown of adverse events.
Look in particular for the proportion of participants who achieve an A1C below 7.0% (the standard glycemic target in adult T2D management) and the proportion who lose 10% or more of body weight. Those two numbers translate trial data into something clinicians can reason about for individual patients.
We will publish a dedicated TRIUMPH-2 results post here as soon as the data is released, and the retatrutide research hub will be updated with the full picture.
Stay Updated
If you’d like a single, plain-English summary the moment TRIUMPH-2 reports, you can join our retatrutide updates list. One email per major milestone, no marketing.
Disclaimer
Retatrutide is an investigational medication. It is not approved by the FDA for any indication, including type 2 diabetes or weight management, and is not commercially available. This post is educational and should not be interpreted as medical advice. For information about how our content is sourced and reviewed, see our editorial policy and medical review policy.
FAQ SECTION
When are TRIUMPH-2 results expected?
Eli Lilly has guided to a 2026 readout for TRIUMPH-2, with the trial part of the broader Phase 3 program supporting a planned New Drug Application submission in 2026. As of May 2026, no topline results have been announced. Detailed results will typically appear first as a Lilly investor press release, followed by peer-reviewed publication and conference presentation.
How is TRIUMPH-2 different from TRANSCEND-T2D-1?
TRANSCEND-T2D-1 was a 537-participant, 40-week Phase 3 trial of retatrutide in adults with type 2 diabetes only, reported in March 2026. TRIUMPH-2 is the larger and longer Phase 3 trial in adults with type 2 diabetes plus obesity, designed as the trial most likely to anchor a U.S. label covering both conditions. Both are placebo-controlled, but TRIUMPH-2 is the more pivotal trial commercially.
Will TRIUMPH-2 be compared head-to-head against tirzepatide?
No. TRIUMPH-2 is placebo-controlled, not active-comparator. The dedicated head-to-head Phase 3 trial against tirzepatide is TRIUMPH-5, registered as ClinicalTrials.gov NCT06662383. TRIUMPH-5 is an 80-week active-comparator trial expected to read out separately. Cross-trial comparisons of TRIUMPH-2 against tirzepatide’s SURPASS program will be informal and should be interpreted cautiously.
Who is eligible for TRIUMPH-2?
TRIUMPH-2 enrolls adults with both type 2 diabetes and obesity, or with type 2 diabetes plus overweight and at least one weight-related comorbidity. Specific eligibility criteria — including A1C range, BMI cutoffs, and exclusions for certain prior therapies — are listed on the trial’s ClinicalTrials.gov record (NCT05929079). The trial is closed to new enrollment as of mid-2026.
What does TRIUMPH-2 mean for someone currently on tirzepatide for type 2 diabetes?
TRIUMPH-2 is investigational data, not a clinical guideline. Even a clean readout would not, on its own, change anyone’s existing treatment. It would, however, provide the clinical evidence base that future guidelines and individual prescribing decisions can draw on. Decisions about switching or adding therapies are highly individual and should be made with the prescribing clinician.
