TRANSCEND-T2D-1 Results: The First Retatrutide Diabetes Readout (March 19, 2026)
TRANSCEND-T2D-1 results, Mar 19, 2026: retatrutide cut A1C by up to 2.0 points and weight by up to 16.8% in 40 weeks in type 2 diabetes. Doses and side effects.
Event date Last verified Primary source Eli Lilly and Company (PR Newswire)
The TRANSCEND-T2D-1 results, released by Lilly on March 19, 2026, were retatrutide's first Phase 3 readout in type 2 diabetes: after 40 weeks, A1C fell by up to 2.0 points and weight by up to 16.8%, against 0.8 points and 2.5% on placebo. Those are Lilly's efficacy estimand figures. The primary source is Lilly's March 19 release.
Key takeaways
- Lilly reported TRANSCEND-T2D-1 on March 19, 2026, the first Phase 3 retatrutide trial in type 2 diabetes and the second Phase 3 readout overall.
- A1C fell 1.7, 2.0 and 1.9 points on 4, 9 and 12 mg against 0.8 on placebo, so the biggest drop was on 9 mg, not 12 mg.
- Weight fell up to 16.8% in 40 weeks, and Lilly said it hadn't plateaued.
- The Lancet published the trial on June 6, 2026, the first peer-reviewed retatrutide Phase 3 paper.
This page records the March announcement and the paper that followed. The trial in full is on the TRANSCEND-T2D-1 page.
What Lilly announced on March 19
TRANSCEND-T2D-1 randomized 537 adults with type 2 diabetes who were managing it with diet and exercise alone. Nobody had taken a diabetes drug for at least 90 days, and A1C at entry was 7.0% to 9.5%. They took 4 mg, 9 mg or 12 mg of retatrutide or placebo once a week for 40 weeks, starting at 2 mg and stepping up every 4 weeks. It was the second Phase 3 trial to report, after TRIUMPH-4 in December 2025.
The TRANSCEND-T2D-1 results by dose
| Measure (40 weeks) | 4 mg | 9 mg | 12 mg | Placebo |
|---|---|---|---|---|
| A1C change, efficacy estimand (from 7.9%) | -1.7 | -2.0 | -1.9 | -0.8 |
| A1C change, treatment-regimen estimand (Lancet) | -1.69 | -1.86 | -1.94 | -0.81 |
| Weight change, efficacy estimand (from 96.9 kg) | -11.5% | -15.5% | -16.8% | -2.5% |
| Nausea | 16.4% | 19.5% | 26.5% | 3.7% |
| Vomiting | 15.7% | 15.0% | 17.6% | 2.2% |
| Stopped because of side effects | 2.2% | 4.5% | 5.1% | 0.0% |
Lilly said weight hadn't plateaued by week 40, and most stomach side effects came while the dose was going up. Counting everyone randomized, weight fell 11.5%, 13.9% and 15.3% against 2.6%.
What the first diabetes result means
The easy mistake is to call 12 mg the strongest dose for blood sugar. On the efficacy estimand, 9 mg did slightly better (2.0 against 1.9 points), and on the Lancet's treatment-regimen estimand, 12 mg edged ahead (1.94 against 1.86). Our read: on A1C, 9 mg and 12 mg did about the same in this trial, while 12 mg took off more weight.
This trial had no active comparator, so it can't tell you how retatrutide stacks up against Mounjaro or Ozempic. The retatrutide vs Mounjaro page sets the numbers side by side with that caveat, and the type 2 diabetes page covers the full diabetes evidence.
What the Lancet paper added
Bajaj and colleagues published TRANSCEND-T2D-1 in The Lancet online on June 6, 2026, the first journal paper for any retatrutide Phase 3 trial; the ADA 2026 news page covers that day. The paper adds that the trial ran at 48 sites in the USA, Mexico and India, that 490 people (91%) finished treatment, and that nobody had severe low blood sugar. It reports 2 deaths, both on 4 mg, both judged unrelated to the study drug.
What came after TRANSCEND-T2D-1
The second diabetes trial, TRANSCEND-T2D-2, reported on October 28, 2026 and put retatrutide against Ozempic 2 mg. The third, TRANSCEND-T2D-3, in people with type 2 diabetes and moderate or severe kidney impairment on basal insulin, has an estimated primary completion of October 2026 on ClinicalTrials.gov and no result as of October 31, 2026.
No approved version exists yet, and anything listed as retatrutide for sale online isn't the drug this trial tested. Lilly's March 19 release described retatrutide as "legally available only to participants in Lilly's clinical trials," a line it has repeated in releases since.
Frequently asked questions
What were the TRANSCEND-T2D-1 results?
After 40 weeks, A1C fell 1.7 points on 4 mg, 2.0 on 9 mg and 1.9 on 12 mg against 0.8 on placebo, from 7.9%. Weight fell 11.5%, 15.5% and 16.8% against 2.5%. All are Lilly's efficacy estimand figures.
Which dose lowered A1C the most?
9 mg, at 2.0 points on the efficacy estimand, just ahead of 12 mg at 1.9. On the treatment-regimen estimand in The Lancet paper, 12 mg was slightly ahead: 1.94 against 1.86.
Who was in TRANSCEND-T2D-1?
537 adults with type 2 diabetes managed with diet and exercise alone, with no diabetes drugs for at least 90 days, an A1C of 7.0% to 9.5% and a BMI of 23 or more.
Was there low blood sugar?
The Lancet paper reports no severe low blood sugar (hypoglycemia). People in the trial weren't on insulin or other diabetes drugs, which is when low blood sugar is most likely.
Sources
- Lilly's triple agonist, retatrutide, demonstrated significant reductions in A1C and weight in first Phase 3 trial for treatment of type 2 diabetes (TRANSCEND-T2D-1 topline). Eli Lilly and Company (PR Newswire), 2026. prnewswire.com
- Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial. The Lancet, 2026. doi.org
- Lilly's retatrutide delivered greater A1C reduction and more than double the weight loss of Ozempic's highest approved dose in head-to-head trial. Eli Lilly and Company (PR Newswire), 2026. prnewswire.com
- TRANSCEND-T2D-3 registry record, NCT06297603. ClinicalTrials.gov, U.S. National Library of Medicine, 2026. clinicaltrials.gov
Dr. Juan Pablo Frías, MD
Physician-Scientist & Clinical Trialist • Endocrinology, Diabetes & Metabolism
Dr. Frías earned his M.D. from Vanderbilt University School of Medicine and completed his endocrinology fellowship at UC San Diego. A principal investigator on landmark incretin trials (including retatrutide, tirzepatide and semaglutide), he reviews all guides on Retatrutide360 for clinical accuracy, dosing safety and evidence fidelity.
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