Lilly says retatrutide cut sleep apnea severity by about 60 percent in a Phase 3 trial

Eli Lilly said on June 6, 2026 that retatrutide, its investigational triple-hormone drug, reduced the severity of moderate-to-severe obstructive sleep apnea by up to 36.1 events per hour, a 60.6 percent drop, and cut knee osteoarthritis pain by up to 4.3 points in a Phase 3 program ^[1][2].

The results come from TRIUMPH-1, an 80-week randomized, double-blind, placebo-controlled trial of 2,339 adults with obesity or overweight. Participants were assigned in equal groups to retatrutide 4 mg, 9 mg, 12 mg or placebo, starting at 2 mg and stepping up every four weeks until they reached their target dose. TRIUMPH-1 included a main obesity trial and two nested "basket" trials, one focused on knee osteoarthritis pain and one on moderate-to-severe obstructive sleep apnea. Lilly said retatrutide met the primary endpoints in each trial at 80 weeks ^[1][2].

In the sleep apnea group, the apnea-hypopnea index fell by up to 36.1 events per hour from a baseline of 58.6 events per hour ^[1][2]. In the osteoarthritis group, WOMAC pain scores fell by up to 4.3 points, or 73.1 percent, from a baseline of 6.0 on a 0-to-10 scale, where higher scores mean worse pain, stiffness and function ^[1][2].

Weight loss in the main trial averaged 47.2 pounds (19.0 percent) at 4 mg, 64.4 pounds (25.9 percent) at 9 mg and 70.3 pounds (28.3 percent) at 12 mg. Among participants on 12 mg, 65.3 percent reached a BMI below 30 and 33.3 percent reached a BMI below 25. In a pre-specified extension, 532 participants who started with a BMI of 35 or higher and continued on 12 mg through 104 weeks lost an average of 85.0 pounds, or 30.3 percent ^[1][2].

A separate trial, TRANSCEND-T2D-1, enrolled 537 adults with type 2 diabetes for 40 weeks. Average A1C fell by up to 2.0 percentage points from a baseline of 7.9 percent. Up to 90 percent of retatrutide participants reached an A1C below 7.0 percent, up to 85 percent reached 6.5 percent or below, and up to 46 percent fell below 5.7 percent, the threshold for normal blood sugar ^[1][2]. Participants on 12 mg lost an average of 36.6 pounds, or 16.8 percent, and Lilly said weight loss had not yet plateaued at 40 weeks ^[1][2]. TRANSCEND-T2D-1 was published in The Lancet, and both trials were presented at the American Diabetes Association's 86th Scientific Sessions on June 6, 2026 ^[1][2].

In TRIUMPH-1, the most common side effects with retatrutide, compared with placebo, were nausea (42.4 percent at 12 mg versus 14.8 percent), diarrhea (32.0 versus 13.5 percent), constipation (26.1 versus 10.9 percent) and vomiting (25.3 versus 4.8 percent). Dysesthesia, a term for altered sensation, was reported by 12.5 percent on 12 mg versus 0.9 percent on placebo. Lilly said these events were generally mild to moderate, that most resolved during treatment and that most participants kept taking the drug. Discontinuation because of side effects was 11.3 percent at 12 mg versus 4.9 percent on placebo ^[1][2].

Why it matters for patients

Retatrutide is an investigational molecule that is legally available only to participants in Lilly's clinical trials, so it cannot be prescribed today ^[1][2]. Whether Lilly has filed or will file for FDA approval, and when, has not been disclosed. The approved medicines named in the same announcement are Lilly's Zepbound (tirzepatide) and Foundayo (orforglipron), which are different molecules ^[1][2].

The results also test a different approach: treating obesity and several of its complications together with one drug rather than one condition at a time, an idea lead investigator Ania Jastreboff of Yale School of Medicine described in the announcement ^[1][2]. The sleep apnea and arthritis figures are average changes for groups, so they do not predict what any single person would experience, and the numbers reported are the best results seen across doses, described as "up to" ^[1][2].

What happens next

Lilly said the TRIUMPH program began in 2023, has enrolled more than 5,800 participants across four global registrational trials, and will produce additional results over the next year. The TRANSCEND-T2D program began in 2024, has enrolled more than 2,050 participants across three trials, and will also report more results over the next year ^[1][2]. No submission date, price or review timeline for retatrutide has been reported.