Retatrutide cuts sleep apnea severity by 60 percent in a TRIUMPH-1 basket trial

Eli Lilly said on June 6, 2026 that retatrutide, an investigational once-weekly triple hormone receptor agonist, met its primary endpoints in two nested "basket" trials run inside its larger TRIUMPH-1 obesity study — one in adults with moderate-to-severe obstructive sleep apnea and one in adults with knee osteoarthritis pain ^[1]. The results were presented at the American Diabetes Association's 86th Scientific Sessions ^[1].

In the sleep apnea basket, retatrutide lowered the apnea-hypopnea index (AHI) — the number of breathing interruptions per hour of sleep — by up to 36.1 events per hour, a 60.6% drop from a baseline of 58.6 events per hour ^[1][2]. In the knee osteoarthritis basket, scores on the WOMAC pain subscale fell by up to 4.3 points, or 73.1%, from a baseline of 6.0 ^[1]. WOMAC is a patient-reported questionnaire scored from 0 to 10, where higher numbers mean worse symptoms ^[1].

One thing to note: Lilly reported these as changes from baseline and used the phrase "up to," which reflects the best-performing dose group. The company's release does not break out how much of the improvement was above placebo in either basket trial, and it does not give the number of participants in each basket ^[1][2]. Those details are not yet known from this announcement.

The weight loss numbers behind it

TRIUMPH-1 (NCT05929066) randomized 2,339 adults with obesity or overweight in equal groups to retatrutide 4 mg, 9 mg, 12 mg, or placebo for 80 weeks ^[1]. Everyone assigned to the drug started at 2 mg weekly and stepped up every four weeks ^[1].

Average weight loss was 47.2 lbs (19.0%) at 4 mg, 64.4 lbs (25.9%) at 9 mg, and 70.3 lbs (28.3%) at 12 mg ^[1]. Among people on 12 mg, 65.3% ended below a BMI of 30 and 33.3% ended below 25 ^[1]. A pre-specified extension enrolled 532 participants who started with a BMI of 35 or higher; those who continued on 12 mg through 104 weeks lost an average of 85.0 lbs (30.3%) ^[1].

Lilly also reported reductions at 80 weeks of up to 41.0% in triglycerides, 24.2% in non-HDL cholesterol, 12.3 mmHg in systolic blood pressure, and 9.5 inches (24.1 cm) in waist circumference ^[1].

Side effects

Stomach-related side effects were common and rose with dose. In TRIUMPH-1, nausea occurred in 28.6%, 38.4%, and 42.4% of the 4 mg, 9 mg, and 12 mg groups versus 14.8% on placebo; diarrhea in 25.2%, 34.1%, and 32.0% versus 13.5%; constipation in 23.8%, 25.9%, and 26.1% versus 10.9%; and vomiting in 10.6%, 22.8%, and 25.3% versus 4.8% ^[1].

Two effects less familiar from other GLP-1 drugs also showed up: dysesthesia, an abnormal skin sensation, in 5.1%, 12.3%, and 12.5% versus 0.9% on placebo, and urinary tract infections in 7.5%, 8.8%, and 8.4% versus 5.3% ^[1]. Lilly said these were generally mild to moderate and mostly resolved during treatment ^[1]. Discontinuations due to adverse events were 4.1%, 6.9%, and 11.3% on retatrutide versus 4.9% on placebo — meaning roughly one in nine people on the top dose stopped because of side effects ^[1].

Why it matters for patients

Obstructive sleep apnea and knee osteoarthritis are two of the conditions that often travel with obesity, and until recently they were treated separately from weight. Zepbound (tirzepatide) is already on the market, and retatrutide is being positioned to address weight plus these complications with one drug ^[1].

But retatrutide is not available. Lilly states plainly that it "is legally available only to participants in Lilly's clinical trials" ^[1][2]. No FDA filing date, approval date, or price has been announced in these materials, so how and when it might reach US patients is not yet known.

The side effect profile also matters for anyone weighing options. The biggest weight and symptom effects came at the highest dose, which also had the highest nausea, vomiting, and dropout rates ^[1]. The nerve-sensation and urinary tract infection signals are worth watching as more data arrive.

What happens next

The TRIUMPH Phase 3 program began in 2023, spans four global registrational trials, and has enrolled more than 5,800 participants, with additional results expected over the next year ^[1]. A separate diabetes program, TRANSCEND-T2D, began in 2024 with more than 2,050 participants across three registrational trials; TRANSCEND-T2D-1 results were published in The Lancet the same day, showing A1C drops of up to 2.0% from a 7.9% baseline at 40 weeks ^[1][2].