New weight loss drug shows promising results for Type 2 diabetes patients
The trial found patients lost nearly 37 pounds over 40 weeks.
A new clinical trial from Eli Lilly and Company suggests its experimental triple hormone drug, retatrutide, could become one of the next major medications in the rapidly growing weight loss and diabetes treatment market.
According to newly released Phase 3 trial data, adults with Type 2 diabetes taking the highest dose of retatrutide lost an average of 36.6 pounds, or 16.8% of their body weight, after 40 weeks of treatment.
The once-weekly injectable medication also lowered A1C levels -- a key measure of long-term blood sugar control -- by an average of 1.7% to 2.0% across doses.
The findings come as demand for GLP-1 medications continues to surge nationwide.
Prescriptions for GLP-1 drugs among U.S. adults increased from 1,884 to 8,819 prescriptions per 100,000 patients between the second quarter of 2021 and the first quarter of 2026, according to Epic research.
What is retatrutide?
Retatrutide is an experimental once-weekly injectable medication being studied for obesity, Type 2 diabetes and other weight-related conditions.
Unlike current blockbuster medications such as Ozempic, Wegovy, Mounjaro and Zepbound, retatrutide targets three hormone receptors -- GIP, GLP-1 and glucagon -- earning it the nickname of a "triple agonist" drug.
Researchers believe the glucagon-targeting effect may help the body burn additional energy while also reducing appetite and improving blood sugar control.
"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.
How much weight did patients lose?
The Phase 3 trial enrolled 537 adults with Type 2 diabetes whose blood sugar levels were not adequately controlled through diet and exercise alone.
Participants had an average baseline A1C of 7.9% and an average body weight of about 213 pounds.
Participants taking the highest 12 mg dose lost an average of 36.6 pounds over the 40-week study period. Researchers also noted participants continued losing weight through the end of the study, suggesting some may not yet have reached a weight-loss plateau.
Earlier studies of retatrutide generated attention after participants without diabetes lost about 24% of their body weight after 48 weeks, among the largest weight-loss results reported so far for an obesity medication.
Lilly also recently shared topline data from another Phase 3 obesity trial, called TRIUMPH-1.
That trial found participants with overweight or obesity but not diabetes who were taking 12 mg of retatrutide lost an average of 70.3 pounds, or 28.3% of their body weight, over 80 weeks, with 45% of participants achieving 30% or more weight loss, a level historically associated with bariatric surgery. At the 4-milligram dose, after just a single dose increase, participants lost an average of 42 pounds, or 19% of their total weight.
How does it compare to current GLP-1 drugs?
For comparison, a major clinical trial published in the New England Journal of Medicine found adults taking semaglutide -- the active ingredient in Wegovy -- lost an average of 14.9% of their body weight over 68 weeks.
Meanwhile, the Phase 3 SURMOUNT-1 trial, also published in the New England Journal of Medicine, found participants taking tirzepatide -- the active ingredient in Zepbound -- lost up to 22.5% of their body weight over 72 weeks.
What are the side effects?
The most commonly reported side effects in the diabetes trial were gastrointestinal symptoms including nausea, diarrhea and vomiting, which researchers said primarily occurred while doses were being increased.
Researchers are also monitoring reports of increased heart rate and skin discomfort among some participants taking the drug.
When could the drug be approved?
Retatrutide remains experimental and has not yet been approved by the FDA.
Medical professionals caution that clinical trials are not complete and the safety and effectiveness will be evaluated by the FDA before any form of retatrutide is available outside of clinical trials.
Anybody buying or selling retatrutide at this time is not dealing with authentic medication and the contents and dosage would be unknown and potentially very dangerous.
Lilly said additional clinical trial data is expected over the next year as the company continues studying the medication for obesity, Type 2 diabetes, obstructive sleep apnea and osteoarthritis linked to obesity.
The company expects to potentially seek FDA approval sometime in late 2027 or early 2028.
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