New Drug Retatrutide Shows Benefits for Diabetes and Weight Loss
Results from recent clinical trials suggest that retatrutide, a first-of-its-kind experimental drug, causes unprecedented levels of weight loss. Its effects on blood sugar for diabetes are comparable to currently available GLP-1 drugs like Ozempic.
Retatrutide, Eli Lilly’s latest weight management and diabetes drug, appears to have outperformed the company’s current product, tirzepatide (Mounjaro, Zepbound), in clinical trials. In fact, people have achieved such dramatic weight loss on retatrutide that experts are talking about the drug as a potential competitor to bariatric surgery.
Retatrutide is the first drug to target receptors for three hormones: GLP-1, GIP, and glucagon. Although glucagon is often thought of as insulin’s opposing force, the combined effects of the medication make it an effective tool for lowering blood sugar as well. Research is still ongoing, but Lilly may soon have enough data to submit retatrutide to the FDA for approval.
What’s different about retatrutide?
Drugs that mimic the body’s natural GLP-1 hormone have been around since 2005, but tirzepatide was the first to target both GLP-1 and the GIP receptors, which act in synergy with GLP-1 and help stimulate insulin release.
Retatrutide goes a step further; in addition to GLP-1 and GIP, it also mimics the hormone glucagon. Glucagon is most famous for the role it plays in sugar metabolism; when a person’s blood sugar drops below a certain point, the hormone tells the liver to stop storing sugar and start releasing it instead. However, glucagon also promotes fat metabolism.
By reducing fat storage, glucagon appears to enhance the weight loss effects of GLP-1. Furthermore, its fat-burning effects make it an exciting potential treatment option for diseases that involve excess fat buildup on internal organs, such as type 2 diabetes and metabolic-associated steatotic liver disease (MASLD).
The most effective obesity medication yet?
The experimental drug has shown particular promise as a treatment for obesity. This first became apparent in 2023 when the company shared the results from a phase 2 trial: study participants who ramped up to 12 mg (the highest dose) lost up to 24% of their body weight in a little less than a year. Those with a body mass index (BMI) over 35 had an even steeper decline in weight loss, showing the effects were greater for people with more severe obesity.
In 2026, results from a larger and longer phase 3 trial supported these findings. Across a year and a half of treatment, participants lost an average of 28% of their body weight. Those who agreed to extend their participation for another six months continued to lose weight, ultimately achieving over a 30% reduction. Study results so far indicate that retatrutide is more effective than any existing weight management medication – and may be almost as effective as bariatric surgery.
Participants achieved such dramatic weight loss that experts at the 2026 ADA conference wondered if retatrutide would be the right choice for all or even most people. In cases of overweight or less severe obesity, 30% body weight loss may be an unnecessary or even harmful treatment target.
Still, regardless of how much weight loss you are targeting or what drug you are taking, it’s important to follow healthy eating patterns (emphasizing protein intake and making sure your diet includes all essential nutrients) and keep up with both aerobic exercise and strength training.
Weight management and health gain
In the most recent trial, retatrutide-driven weight loss was accompanied by other quality-of-life improvements. Study participants with osteoarthritis in their knees started to feel relief. Their average pain rating fell about 70% over the course of the study.
Similar results were observed in a separate trial specifically designed to test the effect of retatrutide therapy on knee pain. Lilly is now recruiting participants for a study exploring the drug’s effects on weight-related low back pain. Meanwhile, participants with chronic obstructive sleep apnea slept better after treatment. Their average number of breathing interruptions throughout the night declined by more than 60%.
The latest research did not explore potential heart and kidney benefits of retatrutide, but researchers are currently collecting and analyzing data to determine its effects on heart and kidney disease. As for liver disease, retatrutide helped 93% of people in an early trial reduce their liver fat below the threshold for a diagnosis of MASLD. Researchers are currently recruiting participants for a phase 3 trial that aims to verify these results.
An effective diabetes drug
The latest study included people with prediabetes; more than 95% of participants reverted to blood sugar levels below the diagnostic threshold for prediabetes.
Lilly also sponsored separate trials to test retatrutide on people with type 2 diabetes. The results demonstrated benefits for blood sugar and weight management, with participants achieving impressive body weight reductions and lower A1C values. In the trials, participants who took the highest dose reduced their A1C values by an average of 2.0%. This was comparable to A1C reductions observed in clinical trials for tirzepatide and Ozempic (semaglutide).
What about the side effects?
Retatrutide has been found so far to be safe and tolerable, with similar side effects to other GLP-1 medications. The most common adverse effects are gastrointestinal issues like nausea and vomiting. Side effects were mostly related to rapidly increasing the drug dose at the start of the clinical trial.
No studies have directly compared the effects of retatrutide and other GLP-1 medications, but vomiting may have been slightly more common in retatrutide trials than in trials for currently available options. Indirect comparisons suggest that, in terms of side effects, retatrutide may be most similar to the triple-strength, 7.2 mg Wegovy dose that the FDA approved in 2026.
The bottom line
In clinical trials, retatrutide has produced unprecedented levels of weight loss for a medication, and the data suggest that it is a very effective diabetes drug as well. Eli Lilly is continuing to collect data on the health benefits of retatrutide before it seeks approval from the FDA.
If and when retatrutide hits the market, it could give people with diabetes another option. Then, as now, choosing a GLP-1 drug will involve weighing the relative importance of weight loss and blood sugar management for improving one’s health.
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