By Katherine Hamilton

Eli Lilly's experimental weight-loss drug retatrutide met the primary and key secondary endpoints in a trial, showing significant reductions in weight loss and blood sugar levels.

Participants of the trial who were taking 12 milligrams of retatrutide lost an average of 36.6 pounds over 40 weeks, the pharmaceutical company said Thursday.

The drug also lowered patients' A1C, a metric for blood-sugar levels, which was the trial's primary endpoint. A1C levels decreased by an average of 1.7% to 2% across doses.

The company said patients who were on the highest dose lost 15.3% of their weight while those in the placebo group lost 2.6%.

Retatrutide contains two other hormones alongside GLP-1s, and has shown higher weight loss potential compared with Lilly's single-hormone weight-loss drugs Mounjaro and Zepbound. Both drugs saw sales more than double in its recent fourth quarter from the previous year.

Weight loss continued through the end of the treatment period without a plateau, Eli Lilly said.

The phase 3 study involved 537 participants with type 2 diabetes. Dosages ranged from 4 milligrams to 12 milligrams.

Patients taking the drug showed improvements across cardiovascular risk factors, as well, Eli Lilly said.

The most common adverse reactions to retatrutide were nausea, diarrhea and vomiting. The reactions mostly happened when dosages were increased.

Lilly plans to share more detailed results at a conference in June.

Shares slipped slightly in premarket trading Thursday to $917.08.

Write to Katherine Hamilton at katherine.hamilton@wsj.com

(END) Dow Jones Newswires

March 19, 2026 07:25 ET (11:25 GMT)

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