Eli Lilly’s obesity drug retatrutide clears late-stage diabetes trial

Eli Lilly The next-generation obesity drug retatrudid has completed its first late-stage trial in patients with Type 2 diabetes, the company said Thursday, helping them manage blood sugar levels and lose weight.

The drug met the study’s primary goal by lowering hemoglobin A1c, a key measure of blood sugar levels, by an average of 1.7% to 2% at different doses over 40 weeks, compared to placebo. Patients began the trial with A1c in the 7% to 9.5% range and were not taking other diabetes medications.

Retatrutide also met the second goal of the study; When evaluated in patients using only the drug, it helped patients on the highest dose lose an average of 16.8% weight, or 36.6 pounds, in 40 weeks. When all participants were analyzed, including those who stopped treatment, the highest dose of the drug helped patients lose 15.3% of their weight.

Patients with Type 2 diabetes have historically had a hard time losing weight, so Lilly was “very excited” to see the drug lead to both a competitive decrease in blood sugar levels and significant weight loss, Ken Custer, president of Lilly Cardiometabolic Health, said in an interview.

He added that the company was also “very pleased” with relatively low treatment discontinuation rates due to side effects of up to 5%.

These are the second late-stage results to date on retatrutide, which works differently than existing injections and appears to be more effective, at least for weight loss. Lilly is betting heavily on retatrutide as the next pillar of its obesity portfolio, after its blockbuster weight-loss injection Zepbound and its upcoming pill, or forglipron.

However, Lilly has not yet applied for approval of the drug for obesity or diabetes. The company expects to report findings from seven additional phase three trials of the drug by the end of the year.

There are no head-to-head trials of retatrutide against other drugs, making direct comparisons of effectiveness difficult.

Still, retatrutide’s A1C reduction doesn’t appear to be the biggest decline Lilly has seen in its portfolio: Zepbound’s highest dose reduced the measurement by more than 2% at week 40. two separate Trials on diabetic patients.

But Custer said retatrutide’s A1C reduction was still “very, very strong” compared to other diabetes medications that don’t target gut hormones.

He also said it would be important to have options in the area of ​​obesity and diabetes because “not everyone will be helped or satisfied with the same treatment.” He added that deciding which drug to take will depend on “the individual tailoring of solutions and patients,” especially in the early stages of diabetes treatment.

For example, patients looking to regulate their blood sugar may benefit from Zepbound or retatrutide, Custer said. But if they want to lose more weight, the latter may be a better option, he said.

In two separate diabetes trials, Zepbound helped patients lose slightly less weight than retatrutide. in one The study called SURPASS-2The highest dose of Zepbound helped patients lose an average of 13.1% of their weight in 40 weeks. inside other study, SURPASS-1The highest dose helped patients lose an average of 11% of their weight at week 40.

Retatrutide’s safety profile was similar to other injectable diabetes and obesity medications, primarily causing gastrointestinal side effects. Approximately 26.5% of patients taking the highest dose experienced nausea, while roughly 22.8% and 17.6% experienced diarrhea and vomiting, respectively.

Low rates of patients experienced dysesthesia, an uncomfortable nerve sensation.

Called the “triple G” drug, retatrutide works by mimicking three hormones that regulate hunger (GLP-1, GIP, and glucagon), rather than just one or two of existing treatments. This appears to have stronger effects on a person’s appetite and satisfaction with eating than other treatments.

Tirzepatide, the active ingredient in Zepbound, mimics GLP-1 and GIP. Wegovy’s active ingredient, Novo Nordisk’s semaglutide, only mimics GLP-1.

Novo is racing to catch up with Lilly as Retatrutide approaches the market. In March 2025, Novo said: agreed to pay Up to $2 billion will be paid for the rights to Chinese pharmaceutical company United Laboratories International’s first experimental drug.

Novo’s newly acquired drug is a clear potential competitor to retatrutide because it similarly uses a three-pronged approach to promote weight loss and regulate blood sugar. But Novo’s treatment is much earlier in development, meaning it will take several years to reach patients.