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
Bajaj HS, Welch M, Shah P, et al. (2026). The Lancet.
Summary
A 40-week phase 3 trial (TRANSCEND-T2D-1) of retatrutide, a GIP, GLP-1 and glucagon receptor agonist, used on its own in adults with type 2 diabetes not controlled by diet and exercise. 537 participants were randomised to one of three retatrutide dose levels or placebo. The primary endpoint was change in HbA1c: it fell by 1.69 to 1.94 percentage points across the retatrutide groups against 0.81 with placebo. Mean body weight changed by -11.5% to -15.3% with retatrutide against -2.6% with placebo. The most common adverse events were gastrointestinal, mostly mild to moderate; 2 to 5% of retatrutide participants stopped treatment because of adverse events, against none on placebo. The trial was funded by Eli Lilly, which develops retatrutide, and six of the ten authors are Lilly employees.