Editorially reviewed · Last updated May 2026 · How we review
TRANSCEND-T2D-1: Retatrutide Phase 3 Diabetes Results (March 2026)
Readout date: March 19, 2026 · 40-week Phase 3 trial · 1,109 participants · Type 2 diabetes
TRANSCEND-T2D-1 was the first Phase 3 trial to test retatrutide specifically in adults with type 2 diabetes. On March 19, 2026, Eli Lilly announced that the trial met its primary endpoint and all key secondary endpoints. Retatrutide produced superior A1C reduction and weight loss compared to placebo across all doses tested.
Headline Results
- A1C reduction: -1.7% to -2.0% across doses at 40 weeks (efficacy estimand)
- Weight loss at 12 mg: -16.8% (-36.6 lbs) at 40 weeks
- Weight loss curve: no plateau through 40 weeks — participants were still losing weight at trial end
- Discontinuation due to adverse events: relatively low across all doses
- Population: adults with type 2 diabetes, mean diabetes duration 2.5 years, not on other diabetes medications
For the full topline summary, see Lilly's press release (March 19, 2026).
Trial Design
| Property | Value |
|---|---|
| Trial name | TRANSCEND-T2D-1 |
| Sponsor | Eli Lilly and Company |
| Phase | 3 |
| Indication | Type 2 diabetes (with inadequate glycemic control on diet & exercise) |
| Treatment duration | 40 weeks |
| Dose arms | 2 mg, 4 mg, 8 mg, 12 mg (placebo control) |
| Titration schedule | 2 → 4 → 6 → 9 → 12 mg over 16 weeks |
| Primary endpoint | Change in A1C from baseline at 40 weeks |
| Key secondary endpoint | Percent change in body weight from baseline at 40 weeks |
| Readout date | March 19, 2026 |
Participants entered the trial with A1C between 7% and 9.5% and were not taking other diabetes medications. The mean duration of diabetes at baseline was 2.5 years.
A1C and Weight Loss by Dose
Retatrutide produced dose-dependent reductions in both A1C and body weight. According to Lilly's topline announcement:
- A1C reduction ranged from -1.7% to -2.0% across the active doses, well above the placebo arm and meeting the primary endpoint with statistical significance.
- Weight loss at the highest dose (12 mg) was 16.8% on the efficacy estimand (analyzing only participants who stayed on treatment) and 15.3% on the treatment-regimen estimand (analyzing all participants including those who discontinued).
- In absolute terms, the 12 mg group lost an average of 36.6 lbs at 40 weeks.
The weight loss observed in TRANSCEND-T2D-1 (16.8%) is lower than the obesity-population results from TRIUMPH-4 (28.7%). This pattern — patients with type 2 diabetes losing less weight on the same GLP-1 drug than non-diabetic populations — is consistent across the entire GLP-1 class (semaglutide, tirzepatide) and is not unique to retatrutide.
Why TRANSCEND-T2D-1 Matters
1. It is the first Phase 3 retatrutide trial in a diabetes population. The Phase 2 type 2 diabetes trial (Rosenstock et al., Lancet 2023) was much smaller and shorter. TRANSCEND-T2D-1 is the registration-quality trial Lilly needs to support a type 2 diabetes indication filing with the FDA.
2. It opens a parallel filing path. Lilly is widely expected to file retatrutide first for obesity (supported by TRIUMPH-1, TRIUMPH-2, TRIUMPH-4) but could simultaneously or near-simultaneously file for type 2 diabetes using TRANSCEND-T2D-1 data. This mirrors how Mounjaro was approved for diabetes (May 2022) before Zepbound for obesity (November 2023).
3. The combined A1C + weight loss profile is differentiated. Patients with type 2 diabetes have historically been harder to treat for obesity than those without diabetes. A drug that lowers A1C by ~2% AND produces ~17% weight loss in this population is a meaningful clinical advance over existing options.
4. No weight loss plateau. The fact that the weight loss trajectory was still declining at 40 weeks suggests longer treatment would produce larger reductions — consistent with what was seen in Phase 2 (no plateau at 48 weeks) and TRIUMPH-4 (continuing decline at 68 weeks).
How It Compares to Other Phase 3 GLP-1 Trials in Diabetes
| Drug | Trial | Duration | Weight loss (top dose) | A1C reduction (top dose) |
|---|---|---|---|---|
| Tirzepatide | SURPASS-2 (vs. semaglutide) | 40 weeks | -11.2 kg | -2.30% |
| Semaglutide | SUSTAIN-1 | 30 weeks | -4.5 kg | -1.55% |
| Retatrutide | TRANSCEND-T2D-1 | 40 weeks | -36.6 lbs (-16.6 kg) | -2.0% |
Direct comparisons between trials should be interpreted cautiously — different populations, baseline characteristics, and protocols affect outcomes. However, TRANSCEND-T2D-1's weight loss figure (~16.6 kg, 16.8%) is the largest reported in any Phase 3 weight-loss trial of a GLP-1 drug in a type 2 diabetes population to date.
What Comes Next
- Full publication is expected later in 2026, likely in New England Journal of Medicine or The Lancet, alongside more detailed safety, body-composition, and subgroup analyses.
- ADA 2026 Scientific Sessions (June 6-10, New Orleans) will include a dedicated TRANSCEND-T2D-1 panel — see our ADA 2026 preview.
- TRANSCEND-T2D-2 and additional TRANSCEND trials are still ongoing.
- Regulatory filing for the diabetes indication is expected as part of Lilly's 2026 retatrutide submission package — see our FDA approval timeline.
Frequently Asked Questions
When were TRANSCEND-T2D-1 results announced?
Eli Lilly announced topline results on March 19, 2026 via press release. Full peer-reviewed publication is expected later in 2026.
How much weight did people lose in TRANSCEND-T2D-1?
At the highest dose (12 mg), participants lost an average of 16.8% of body weight (-36.6 lbs) at 40 weeks on the efficacy estimand, and 15.3% on the treatment-regimen estimand (which includes participants who discontinued). The weight loss curve had not plateaued at the 40-week endpoint.
What was the A1C reduction in TRANSCEND-T2D-1?
Across the active doses, retatrutide lowered A1C by 1.7% to 2.0% at 40 weeks, meeting the trial's primary endpoint with statistical significance. Participants entered with baseline A1C between 7% and 9.5% and were not on other diabetes medications.
Is retatrutide FDA approved for diabetes?
No. Retatrutide is not FDA approved for any indication. TRANSCEND-T2D-1 is the first Phase 3 trial supporting a potential type 2 diabetes filing. Lilly has guided that retatrutide regulatory submissions will occur in 2026, with a likely FDA decision in 2027-2028. See our FDA approval timeline for the full filing outlook.
How does TRANSCEND-T2D-1 weight loss compare to TRIUMPH-4?
TRIUMPH-4 (obesity + knee osteoarthritis, Dec 2025) showed 28.7% weight loss at 12 mg over 68 weeks. TRANSCEND-T2D-1 (type 2 diabetes, Mar 2026) showed 16.8% at 12 mg over 40 weeks. The difference is consistent with the broader GLP-1 class — patients with type 2 diabetes typically lose less weight on the same drug than non-diabetic populations. The longer treatment duration in TRIUMPH-4 also contributes.
Sources
- Eli Lilly and Company. (March 19, 2026). Lilly's triple agonist, retatrutide, demonstrated significant reductions in A1C and weight in first Phase 3 trial for treatment of type 2 diabetes. PRNewswire press release
- Constantino, A.K. (March 19, 2026). Eli Lilly's obesity drug retatrutide clears late-stage diabetes trial. CNBC
- Gardner, J. (March 19, 2026). Lilly's three-pronged obesity drug hits goal in large diabetes trial. BioPharma Dive
- Flynn Mogensen, J. (March 19, 2026). Experimental GLP-3 weight-loss drug retatrutide shows promising results in clinical trial. Scientific American
Medical disclaimer: This page summarizes publicly available topline results from a clinical trial. Retatrutide is not FDA approved and is not available outside of clinical trials. This is informational only and not medical advice. Always consult a qualified healthcare provider before making decisions about medications. glp3.wiki is not affiliated with Eli Lilly or any pharmaceutical company.
Sources
Related reading
Retatrutide Phase 3 Trials 2026: TRIUMPH & TRANSCEND-T2D Tracker
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Retatrutide FDA Approval Timeline 2026-2028: Filing & Status
TRANSCEND-T2D-1 and TRIUMPH-3 are in. Projected FDA filing 2026-27, approval 2027-28. Live timeline.
TRIUMPH-3: Retatrutide 24.2% Weight Loss at 72 Weeks (March 2026)
Retatrutide produced 24.2% mean weight loss at 72 weeks in a cardiovascular-risk population. Presented at ACC, March 5, 2026.
TRIUMPH-4: Retatrutide 28.7% Weight Loss in Obesity + Knee OA (Dec 2025)
First retatrutide Phase 3 readout (December 2025) — 28.7% weight loss at 12 mg, significant knee pain relief, and the dysesthesia signal first observed at scale.
Retatrutide for Type 2 Diabetes
Retatrutide's Phase 2 T2D data showed HbA1c reductions of -2.02% and weight loss of -16.94% — with the TRANSCEND Phase 3 program underway.