TLDR
- Eli Lilly’s next-gen “triple-G” drug retatrutide passed its first late-stage trial in Type 2 diabetes patients
- It lowered blood sugar (HbA1c) by 1.7%–2% vs 0.8% for placebo at 40 weeks
- Patients lost up to 16.8% of their body weight at the highest dose
- Retatrutide targets three hormones (GLP-1, GIP, glucagon) vs one or two for existing drugs
- Lilly has not yet filed for FDA approval; seven more Phase 3 trial readouts are expected by year-end
Eli Lilly’s experimental drug retatrutide met the main goal of its first late-stage diabetes trial, cutting blood sugar levels and driving weight loss in Type 2 diabetes patients, the company announced Thursday.
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. https://t.co/OFBUzypgGt
— The Wall Street Journal (@WSJ) March 19, 2026
The 40-week trial tested retatrutide in patients with Type 2 diabetes who were managing their condition through diet and exercise alone. Patients entered the trial with an HbA1c — a standard blood sugar marker — in the 7%–9.5% range.
Retatrutide reduced HbA1c by an average of 1.7% to 2% across doses, compared with 0.8% for placebo. That met the trial’s primary goal.
On the weight loss side, patients taking the highest dose lost an average of 16.8% of their body weight when counting only those who stayed on the drug. When all participants were included — even those who stopped treatment — the figure was 15.3%.
For context, Lilly’s existing drug Zepbound helped diabetes patients lose between 11% and 13.1% of their weight in comparable 40-week trials. Retatrutide’s weight loss numbers are higher, though there are no head-to-head trials between the two.
Scotiabank analyst Louise Chen called it “the highest levels of weight loss we’ve seen from an obesity drug to date” in a patient group that historically struggles to shed weight.
J.P. Morgan analysts offered a more measured view, noting that the drug’s results are partly offset by higher rates of adverse events when compared to Lilly’s diabetes drug Mounjaro.
How Retatrutide Works
Retatrutide is a once-weekly injection that activates three hormone receptors — GLP-1, GIP, and glucagon — earning it the nickname “triple-G.” That’s one more than Zepbound (tirzepatide), which targets GLP-1 and GIP, and two more than Novo Nordisk‘s Wegovy (semaglutide), which only hits GLP-1.
The idea is that hitting all three pathways suppresses appetite, controls blood sugar, and increases calorie burning at the same time.
Side effects were mostly gastrointestinal. Around 26.5% of patients on the highest dose reported nausea, 22.8% had diarrhea, and 17.6% experienced vomiting. Discontinuation due to side effects reached up to 5%, which Lilly described as relatively low.
A small number of patients experienced dysesthesia — an unpleasant nerve sensation.
Where Lilly Stands on Approval
Lilly has not yet filed for regulatory approval of retatrutide for either obesity or diabetes. Thursday’s data is only the second Phase 3 readout for the drug.
The company expects results from seven additional Phase 3 trials before the end of 2025, covering a range of patient populations.
Lilly is also preparing to launch its obesity pill orforglipron in Q2 of this year, pending FDA approval.
Novo Nordisk, meanwhile, is working to close the gap. In March 2025, Novo paid up to $2 billion for the rights to a triple-receptor drug from United Laboratories International — but that treatment is still in early development and years away from patients.
Lilly stock (LLY) was down slightly in premarket trading on Thursday following the results.
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