Eli Lilly's experimental diabetes drug cut weight by 17% in a study

Eli Lilly $LLY said its experimental drug retatrutide helped patients with Type 2 diabetes shed up to 16.8% of their body weight over 40 weeks in a Phase 3 trial, outpacing all diabetes drugs now available.

The company announced results from TRANSCEND-T2D-1, a Phase 3 trial evaluating retatrutide as an adjunct to diet and exercise in 537 adults with Type 2 diabetes and inadequate blood sugar control. Patients had a mean diabetes duration of 2.5 years.

The drug reached its main goal by lowering A1C, which measures long-term blood sugar control, by up to 2.0% over 40 weeks. By comparison, the placebo group saw a 0.8% drop.  For a key secondary endpoint, patients on the highest 12 mg dose lost an average of 36.6 pounds, or 16.8% of their body weight, in an analysis limited to those who completed treatment. Including patients who discontinued, weight loss at the highest dose averaged 15.3%. Weight loss continued through the end of the treatment period, with no plateau observed, Lilly said.

"For many people with type 2 diabetes, it is a struggle to achieve both A1C control and weight loss, since obesity has historically been harder to treat for those with type 2 diabetes," Kenneth Custer, executive vice president and president of Lilly Cardiometabolic Health, said in a statement.

Unlike Mounjaro and Novo Nordisk's Ozempic, which act on one or two hormonal pathways, retatrutide is designed to activate receptors for three gut hormones: GLP-1, GIP and glucagon. The drug is taken once weekly.

At the 12 mg dose, nausea was reported by 26.5% of patients, diarrhea by 22.8%, and vomiting by 17.6%, Lilly said. Roughly 5% of patients on the 12 mg dose left the study because of side effects. Dysesthesia — an unpleasant nerve sensation — was reported at low rates across all doses; the majority of those cases resolved before the trial concluded, Lilly said.

The drug also showed improvements in cardiovascular risk factors including non-HDL cholesterol, triglycerides and systolic blood pressure, Lilly said.

Eli Lilly stock was largely flat in Thursday morning trading, while Novo Nordisk stock fell 2.3%.

More detailed results will be presented at the American Diabetes Association's Scientific Sessions in June. The company has seven more Phase 3 retatrutide trials with results due before the end of 2026, according to CNBC. Retatrutide is not approved for any indication and remains legally available only to clinical trial participants.