Retatrutide Cuts Weight 20.8% in Type 2 Diabetes, and Lilly Plans to File It as a Biologic

Eli Lilly presented detailed TRIUMPH-2 results for retatrutide, its once-weekly GIP, GLP-1 and glucagon triple agonist, at EASD and in The Lancet on 29 September 2026. The 80-week Phase 3 trial randomised 1,152 adults with type 2 diabetes and obesity or overweight to 4 mg, 9 mg, 12 mg or placebo.
Weight fell by 12.7%, 19.1% and 20.8% on the three doses against 4.0% on placebo, on the efficacy estimand. At 12 mg, patients with a baseline BMI of 35 or more lost 23.4%, and 59.5% no longer met the BMI definition of obesity.
A1C fell by 1.4, 1.6 and 1.5 points from a baseline of 7.7%, against 0.2 on placebo, and up to 40.0% of patients reached an A1C below 5.7%, an endpoint not controlled for multiplicity.
Diarrhoea reached 33.6% and nausea 28.0% at 12 mg, against 13.2% and 8.0% on placebo. Dysesthesia, abnormal skin sensation, occurred in 7.3% at 12 mg against 0.7%. Discontinuation for adverse events was 3.8%, 11.6% and 7.7% by dose, against 4.9%. Lilly plans a Biologics License Application in the first quarter of 2027.

CI read

The efficacy is the headline. The filing route and a sensory side effect are the details that will shape the label.

Lilly is filing the classification it is litigating. The release says it will submit a Biologics License Application, the status Lilly argued for at the Seventh Circuit on 24 September because it carries 12 years of exclusivity. How the court rules will decide whether that filing route holds.
Dysesthesia is the side effect to watch. A dose-related skin-sensation disturbance at ten times the placebo rate is not part of the familiar GLP-1 profile of gastrointestinal effects. How it is described in the label will matter in a market where Zepbound and Wegovy set the tolerability reference.
Dose choice is not straightforward. The 9 mg dose gave the largest A1C reduction but the highest discontinuation rate, while 12 mg added weight loss with fewer dropouts. With Foundayo daily, tirzepatide weekly and now a triple agonist, Lilly covers three tiers of the market on the day Novo licensed a weekly oral from Hengrui.