The experimental drug produced substantial weight loss and improved blood sugar control in adults with obesity and type 2 diabetes, though it has not yet been approved.
Retatrutide, an experimental obesity and diabetes treatment being developed by Eli Lilly, has produced some of the strongest weight-loss and blood sugar results yet seen in late-stage testing, according to research published in The Lancet and presented at the European Association for the Study of Diabetes meeting in Milan. In the largest study of its kind, the drug helped adults with obesity and type 2 diabetes lose up to nearly a fifth of their body weight over 80 weeks, while also improving glucose control and several markers linked with cardiovascular risk.
The treatment works differently from currently marketed weight-loss injections such as Wegovy and Mounjaro because it acts on three hormone pathways rather than one or two. Retatrutide targets GLP-1, GIP and glucagon receptors, a combination designed to curb appetite, improve blood sugar regulation and raise energy expenditure. Researchers said the drug showed “substantial reduction in body weight alongside glycaemic control and cardiometabolic risk factors, with a safety profile generally similar to other molecules with GLP-1 receptor agonist activity”.
In the phase 3 trial, 2,047 adults were enrolled across eight countries, with 1,152 randomly assigned to receive retatrutide or placebo alongside lifestyle advice. After 80 weeks, those given the 4 mg dose lost an average of 11.9% of their body weight, rising to 16.8% with 9 mg and 18.8% with 12 mg, compared with 5.1% for placebo. Nearly half of those on the highest dose lost at least 20% of their starting weight, while almost a third lost at least 25%. The same group also saw major improvements in HbA1c, the measure doctors use to assess average blood sugar over the previous two to three months, with 72% reaching a level of 6.5% or lower.
The findings add to earlier evidence that retatrutide may be one of the most potent weight-loss medicines in development. Separate reports on earlier and parallel trials have pointed to even larger reductions in body weight in people without diabetes, with higher doses consistently producing greater losses and the top dose approaching or exceeding 28% in some studies. Retatrutide has not yet been approved by regulators in the US, the UK or elsewhere, and the most common side-effects in the latest trial were gastrointestinal, including diarrhoea and nausea. Researchers also said that further work is needed to clarify the drug’s longer-term safety and to understand its role alongside the fast-growing class of incretin-based obesity treatments.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
