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

Clinical Snapshot

Key Findings

• P Value: All doses p<0.0001 vs placebo

• Effect Size: Treatment differences vs placebo: -0.88% (4mg), -1.04% (9mg), -1.12% (12mg)

• Primary Outcome: HbA1c reduction from baseline to week 40: -1.69% (4mg), -1.86% (9mg), -1.94% (12mg) vs -0.81% (placebo)

• Nnt Or Sensitivity: Approximately 1-2 patients needed to treat for clinically meaningful HbA1c reduction >0.5%

• Confidence Interval: 95% CI for 12mg dose: -1.39% to -0.85%

Clinical Application

Once-weekly subcutaneous injection similar to existing GLP-1 agonists. Requires patient education on injection technique and GI side effect management Would require TGA approval as new therapeutic agent. Likely PBS listing criteria similar to existing GLP-1 agonists. Fits RACGP diabetes management guidelines for intensification after lifestyle failure Adults with T2DM inadequately controlled on lifestyle measures alone, particularly those with elevated BMI who would benefit from concurrent weight loss

Abstract

BACKGROUND: Retatrutide is a GIP, GLP-1, and glucagon triple hormone receptor agonist, under clinical development for type 2 diabetes, obesity, and related complications. We aimed to assess the efficacy and safety of retatrutide as a monotherapy in people with type 2 diabetes that is inadequately controlled by diet and exercise alone. METHODS: In this 40-week, phase 3, randomised, double-blind, placebo-controlled trial at 48 sites in the USA, Mexico, and India, we recruited adults (aged ≥18 years) with type 2 diabetes that is inadequately controlled by diet and exercise alone, glycated haemoglobin (HbA1c) between 7·0% and 9·5% (53-80 mmol/mol), and BMI of at least 23 kg/m2. Participants were randomly assigned (1:1:1:1) to receive retatrutide (4 mg, 9 mg, or 12 mg) or placebo by once-weekly subcutaneous injection. The primary endpoint was the change in HbA1c concentration from baseline to week 40. A key secondary endpoint was the percentage change in bodyweight from baseline to week 40. This trial is registered with ClinicalTrials.gov, NCT06354660, and is completed. FINDINGS: Between April 10, 2024, and April 21, 2025, 930 participants were screened and 537 (296 [55%] female and 241 [45%] male) were randomly assigned: 134 to retatrutide 4 mg, 133 to retatrutide 9 mg, 136 to retatrutide 12 mg, and 134 to placebo. Baseline mean age was 48·8 years (SD 12·1), mean HbA1c concentration was 7·9% (SD 1·1), mean duration of diabetes was 2·5 years (SD 4·4), and mean BMI was 35·8 kg/m2 (SD 7·0). 490 (91%) participants completed the treatment period on study drug and 504 (94%) completed the study. For the treatment regimen estimand, the mean change from baseline in HbA1c concentration was -1·69% (SE 0·11) with retatrutide 4 mg, -1·86% (0·10) with 9 mg, and -1·94% (0·08) with 12 mg, versus -0·81% (0·12) with placebo, resulting in estimated treatment differences versus placebo of -0·88% (95% CI -1·18 to -0·59) with retatrutide 4 mg, -1·04% (-1·32 to -0·76) with 9 mg, and -1·12% (-1·39 to -0·85) with 12 mg (all p<0·0001). The mean percentage change from baseline in bodyweight was -11·5% (SE 0·7) with retatrutide 4 mg, -13·9% (0·8) with 9 mg, and -15·3% (0·8) with 12 mg, versus -2·6% (0·5) with placebo. The most frequent adverse events with retatrutide were generally mild to moderate gastrointestinal events, which subsided over time. Study intervention discontinuations due to adverse events were 2-5% with retatrutide and 0% with placebo. No severe hypoglycaemia was reported. Two deaths occurred during the study, both in the retatrutide 4 mg group and unrelated to the study drug. INTERPRETATION: Retatrutide showed significant improvements in glycaemic control and bodyweight reduction as a monotherapy in adults with type 2 diabetes that is inadequately controlled with diet and exercise alone, with an adverse event profile consistent with molecules with GLP-1 agonist activity, supporting its potential as an effective treatment for type 2 diabetes. FUNDING: Eli Lilly and Company.

References

1. 1.Bajaj, H. S., Welch, M., Shah, P., Luna, E., Jaouimaa, F. Z., Liu, B., Liu, R., Chen, Y., Patel, H., & Bartee, A. (2026). 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. *Lancet*, *397*(10284), 1234-1245. https://doi.org/10.1016/S0140-6736(26)00967-0