Weekly retatrutide cut sleep-apnea breathing pauses in two phase 3 trials, including in people with diabetes

Two late-stage trials of retatrutide, an experimental once-weekly injection, found it reduced obstructive sleep apnea (OSA) in adults with overweight or obesity. The results were published in the New England Journal of Medicine (Grunstein et al.) and reported by Medical Xpress on 24 October 2026.

The trials

• TRIUMPH-1-OSA enrolled people without type 2 diabetes, TRIUMPH-2-OSA people with it.
• Both were randomised, double-blind and placebo-controlled. Participants had a BMI of at least 27 and at least 15 breathing pauses per hour of sleep; they got 4 mg, 9 mg or 12 mg of retatrutide or placebo weekly for 80 weeks, with overnight sleep-lab tests.
• Retatrutide acts on three hormone receptors (GLP-1, GIP and glucagon), whereas semaglutide acts on one and tirzepatide on two.

Results

• All three doses reduced breathing interruptions more than placebo, in both trials.
• At the two higher doses, pauses fell by about 25 per hour on average (roughly 40%), versus about 10 with placebo. At 4 mg the drop was about 23 per hour, with average weight loss of 12.5%.
• Among people on higher doses, 39%–52% improved to no or mild OSA without excessive daytime sleepiness, versus about 13% on placebo. Participants with diabetes lost 18%–19% of body weight versus about 6% on placebo.

Limitations

These are well-designed randomised trials, but retatrutide is not approved for OSA or obesity, and the reports we reviewed did not detail side effects or long-term outcomes such as heart events. Benefits were measured over 80 weeks; what happens after stopping is unknown. Medical Xpress notes that many people struggle with CPAP masks — anyone with sleep apnea should discuss options with their doctor.