Investigational · not FDA approved
Editorially reviewed · Last updated September 8, 2026 · How we review
TRANSCEND-T2D-1: Retatrutide Phase 3 Diabetes Results
Readout date: March 19, 2026 · 40-week Phase 3 trial · 537 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. Full results were published in The Lancet on June 6, 2026.
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: 2.2%, 4.5%, and 5.1% at 4 mg, 9 mg, and 12 mg, versus 0.0% with placebo
- 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 | 4 mg, 9 mg, 12 mg, and placebo |
| 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 (estimating efficacy while on treatment without rescue medication) 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 peer-reviewed paper also reports the treatment-regimen estimand, which estimates outcomes regardless of treatment discontinuation or rescue medication:
| Group | A1C change at 40 weeks (percentage points) | Weight change at 40 weeks |
|---|---|---|
| Retatrutide 4 mg | -1.69 | -11.5% |
| Retatrutide 9 mg | -1.86 | -13.9% |
| Retatrutide 12 mg | -1.94 | -15.3% |
| Placebo | -0.81 | -2.6% |
These figures should not be substituted for the efficacy-estimand results above. The study tested monotherapy in adults whose diabetes was inadequately controlled with diet and exercise alone, not an insulin-replacement strategy. Source: Bajaj et al., The Lancet.
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 provides evidence in early type 2 diabetes. Participants had a mean diabetes duration of 2.5 years and were not using other diabetes medicines. Results may differ in people with longer-standing disease or those using insulin.
3. Benefits must be read alongside adverse events. Gastrointestinal events were the most common adverse events. The published trial reported no severe hypoglycemia, but that finding is specific to this trial population and does not establish safety when combined with other diabetes medicines.
4. The study ends at 40 weeks. Lilly reported no weight-loss plateau by that point. It does not tell us how much additional weight loss the same participants would achieve over longer treatment.
How It Compares to Other Phase 3 GLP-1 Trials in Diabetes
TRANSCEND-T2D-1 compared retatrutide with placebo, not tirzepatide or semaglutide. Its results therefore establish benefit against placebo in this population, not superiority to another diabetes medicine.
Comparing published trials requires matching baseline A1C, diabetes duration, background medicines, follow-up, and estimand. For the broader context, see retatrutide for type 2 diabetes.
What Comes Next
- Full publication is available: Bajaj et al., The Lancet, June 6, 2026.
- ADA presentation: see the ADA 2026 summary.
- Further diabetes evidence: the TRANSCEND program includes other treatment settings; results from this monotherapy trial cannot answer every combination-treatment question.
- Regulatory status: Lilly's July update described a planned Q1 2027 U.S. submission for retatrutide. It did not establish a diabetes approval date. See the 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 results were published online in The Lancet on June 6, 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 announced a planned Q1 2027 U.S. submission in July 2026; that is not an approval date or confirmation of a diabetes indication. 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 populations and treatment durations differ, so these figures cannot isolate the effect of diabetes or predict what longer treatment would do.
Sources
-
Bajaj, H.S., et al. (2026). TRANSCEND-T2D-1. The Lancet. Published trial
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ClinicalTrials.gov. NCT06354660
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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
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Constantino, A.K. (March 19, 2026). Eli Lilly's obesity drug retatrutide clears late-stage diabetes trial. CNBC
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Gardner, J. (March 19, 2026). Lilly's three-pronged obesity drug hits goal in large diabetes trial. BioPharma Dive
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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.
How we keep this honest
- What this is
- Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
- Regulatory status
- Retatrutide and similar peptides are investigational — not approved by the FDA or any regulator. Semaglutide and tirzepatide are prescription-only medicines, available only through a licensed prescriber.
- Our standard
- Every claim traces to a primary source. We label the strength of evidence and flag estimates as estimates — never as clinical fact.
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- We don’t sell, supply, or link to suppliers of any medicine, and aren’t affiliated with any manufacturer.
Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.
Sources
- TRANSCEND-T2D-1 published trial
The Lancet / PubMed
- ADA 2026 trial results
Eli Lilly
- TRANSCEND-T2D-1 registry
ClinicalTrials.gov
Grounded in primary sources
NEJM
The Lancet
JAMA
FDA
ClinicalTrials.govRelated reading
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