Key facts
- Drug / target: tirzepatide, once weekly, subcutaneous — a dual GIP/GLP-1 receptor agonist.
- Sponsor: Eli Lilly and Company.
- Design: two phase 3, randomized, double-blind, placebo-controlled, parallel-group trials.
- Population: adults with moderate-to-severe obstructive sleep apnea and obesity. Trial 1 = not on positive airway pressure (PAP); trial 2 = already on PAP.
- Intervention: maximum tolerated dose of tirzepatide (10 mg or 15 mg) or matching placebo, 1:1, for 52 weeks.
- Primary endpoint: change in the apnea-hypopnea index (AHI) from baseline.
- Headline result: AHI treatment difference −20.0 events/hour (trial 1) and −23.8 events/hour (trial 2), both P<0.001.
- Registration: NCT05412004 — ClinicalTrials.gov.
- Publication: New England Journal of Medicine, 2024 — PMID 38912654.
What was SURMOUNT-OSA?
SURMOUNT-OSA was a pair of phase 3, double-blind, randomized, placebo-controlled trials that tested whether tirzepatide could treat obstructive sleep apnea in adults who also had obesity. It was sponsored by Eli Lilly and published in the New England Journal of Medicine in 2024 (PMID 38912654).
Obstructive sleep apnea is characterized by disordered breathing during sleep and is associated with major cardiovascular complications, and excess adiposity is a well-established risk factor. That link is what made a weight-lowering metabolic drug a plausible therapy for a breathing disorder. Rather than measuring only weight, SURMOUNT-OSA set out to test whether tirzepatide changed the disease itself — measured by the apnea-hypopnea index over 52 weeks. The programme is registered as NCT05412004 on ClinicalTrials.gov.
This is a different question from the weight-loss trials that made the drug famous. Where SURMOUNT-1 measured how much weight tirzepatide produced in obesity, SURMOUNT-OSA measured whether that intervention improved a specific, objectively scored condition — sleep apnea.
Who was in it?
SURMOUNT-OSA enrolled adults with moderate-to-severe obstructive sleep apnea and obesity, and it split them across two parallel trials that mirror how the condition is managed in the real world. Trial 1 enrolled participants who were not receiving positive airway pressure (PAP) therapy at baseline; trial 2 enrolled participants who were already using PAP.
The population was, by design, severely affected. At baseline the mean AHI was 51.5 events per hour in trial 1 and 49.5 events per hour in trial 2 — both firmly in the severe range — and the mean body-mass index was 39.1 and 38.7 respectively. Running the two trials in parallel let the investigators see whether tirzepatide helped both people managing their apnea without a device and people already on the standard mechanical treatment.
What did participants receive?
Participants were assigned in a 1:1 ratio to receive either the maximum tolerated dose of once-weekly subcutaneous tirzepatide — 10 mg or 15 mg — or a matching placebo, for 52 weeks. Tirzepatide is a dual GIP and GLP-1 receptor agonist; the underlying molecule is covered in our tirzepatide research summary.
Describing the assigned regimen is reporting what the trial did — it is not a dosing instruction. Tirzepatide is prescription-only, and the dose any individual might use is a clinical decision, not something to infer from a trial protocol.
Primary results
The primary endpoint was the change in the apnea-hypopnea index from baseline at week 52. The AHI counts apneas and hypopneas per hour of sleep, so a larger negative number means fewer breathing disruptions overnight.
In trial 1, the mean change in AHI at week 52 was −25.3 events per hour with tirzepatide (95% CI −29.3 to −21.2) versus −5.3 events per hour with placebo (95% CI −9.4 to −1.1), for an estimated treatment difference of −20.0 events per hour (95% CI −25.8 to −14.2; P<0.001). In trial 2, the mean change was −29.3 events per hour with tirzepatide (95% CI −33.2 to −25.4) versus −5.5 with placebo (95% CI −9.9 to −1.2), for an estimated treatment difference of −23.8 events per hour (95% CI −29.6 to −17.9; P<0.001).
| Change in AHI at week 52 (events/hour) | Tirzepatide | Placebo | Treatment difference |
|---|---|---|---|
| Trial 1 (not on PAP; baseline AHI 51.5) | −25.3 (95% CI −29.3 to −21.2) | −5.3 (95% CI −9.4 to −1.1) | −20.0 (95% CI −25.8 to −14.2); P<0.001 |
| Trial 2 (on PAP; baseline AHI 49.5) | −29.3 (95% CI −33.2 to −25.4) | −5.5 (95% CI −9.9 to −1.2) | −23.8 (95% CI −29.6 to −17.9); P<0.001 |
Both trials pointed the same way: a substantial reduction in the apnea-hypopnea index with tirzepatide relative to placebo, whether or not participants were also using a PAP device. Against a severe baseline near 50 events per hour, a treatment difference of roughly 20 to 24 events per hour is a large absolute change in how often breathing is disrupted overnight.
Secondary results and weight
The key multiplicity-controlled secondary endpoints included the percent change in AHI and in body weight, plus changes in hypoxic burden, patient-reported sleep impairment and disturbance, high-sensitivity C-reactive protein (hsCRP), and systolic blood pressure. The published trial reports significant improvements with tirzepatide compared with placebo across all of these prespecified key secondary endpoints.
Consistent with tirzepatide's established effects, participants lost weight — the trial names body weight as one of the endpoints that improved. Because this page reports only figures confirmed in the peer-reviewed abstract, we do not attach a specific weight-loss percentage to SURMOUNT-OSA here; for the magnitude of weight loss tirzepatide produces in a dedicated obesity trial, see our summary of SURMOUNT-1, and for the broader class picture, peptides for weight loss.
One nuance worth stating plainly: excess weight is a recognized driver of obstructive sleep apnea, and tirzepatide reduced both weight and the AHI. The trial reports these as parallel clinical outcomes; it was not designed to prove precisely how much of the sleep-apnea benefit came from weight change versus other effects of the drug.
Safety and side effects reported
The most frequently reported adverse events with tirzepatide were gastrointestinal in nature and were mostly mild to moderate in severity — the pattern already well documented for this drug class. This page reports only the safety characterization stated in the published record and does not assign rates to specific symptoms.
For a fuller picture of the side effects seen across the GIP/GLP-1 and GLP-1 classes — nausea, diarrhea, vomiting and constipation, typically worst during dose escalation, plus class warnings — see the dedicated sections in our weight-loss peptides guide and the drug-level tirzepatide summary.
Limitations and what it does not prove
SURMOUNT-OSA is a landmark result, but it has boundaries that matter when the headline gets quoted:
- It studied a specific population. Everyone enrolled had both moderate-to-severe obstructive sleep apnea and obesity. The result applies most directly to people like those enrolled — it does not automatically extend to sleep apnea in people without obesity, or to mild disease.
- It does not fully isolate a mechanism. Tirzepatide lowered both weight and the AHI, but the trial reports parallel outcomes; it cannot precisely partition the sleep-apnea benefit into weight loss versus other effects.
- It is a comparison against placebo, not against PAP or other drugs. SURMOUNT-OSA shows tirzepatide beat placebo on the AHI; it does not establish that a medicine should replace positive airway pressure, and trial 2 participants were on PAP throughout.
- It reflects 52 weeks of continued treatment. The trial describes one year on the drug; it does not tell you what happens to the AHI if treatment stops.
None of this diminishes the finding. It simply keeps it the right size: strong, consistent evidence in a defined population, not a universal claim.
Why SURMOUNT-OSA matters
SURMOUNT-OSA is the pivotal evidence behind tirzepatide's obstructive-sleep-apnea indication. For decades, obstructive sleep apnea in people with obesity had one dominant treatment — positive airway pressure — and no medicine shown to move the apnea-hypopnea index in a large, controlled trial. SURMOUNT-OSA showed that a metabolic drug could reduce the AHI meaningfully in both untreated patients and those already using PAP, positioning tirzepatide as the first pharmacologic option with this kind of outcome data for the condition.
The practical consequence is that the conversation around tirzepatide shifted from weight on a scale to a specific, objectively measured disease. It reinforced the reframing of the newer incretin-based drugs as metabolic medicines with effects beyond weight. For the wider map of which weight-loss peptides carry trial-grade evidence — and which do not — see our pillar guide on peptides for weight loss, or browse all research articles.
Frequently asked questions
What did the SURMOUNT-OSA trial show?
SURMOUNT-OSA was two phase 3, double-blind, randomized, placebo-controlled trials in adults with moderate-to-severe obstructive sleep apnea and obesity. Over 52 weeks, tirzepatide lowered the apnea-hypopnea index far more than placebo: the estimated treatment difference was -20.0 events per hour in trial 1 (participants not on positive airway pressure) and -23.8 events per hour in trial 2 (participants using positive airway pressure), both P<0.001. Tirzepatide also reduced body weight and improved several secondary measures.
What is the apnea-hypopnea index and why does it matter here?
The apnea-hypopnea index (AHI) counts the number of apneas and hypopneas — pauses and shallow-breathing episodes — per hour of sleep, and it is the standard way to grade obstructive sleep apnea severity. In SURMOUNT-OSA the mean baseline AHI was 51.5 events per hour in trial 1 and 49.5 in trial 2, both in the severe range. Change in AHI was the trial's primary endpoint, so it is the measure that carried the primary result.
Why did SURMOUNT-OSA have two separate trials?
SURMOUNT-OSA ran as two parallel trials to reflect how sleep apnea is managed in practice. Trial 1 enrolled adults who were not being treated with positive airway pressure (PAP) at baseline, and trial 2 enrolled adults who were already using PAP therapy. Testing tirzepatide in both groups showed a consistent reduction in the apnea-hypopnea index whether or not participants were also using a PAP device.
What dose of tirzepatide was used in SURMOUNT-OSA?
Participants were assigned in a 1:1 ratio to receive the maximum tolerated dose of once-weekly tirzepatide — either 10 mg or 15 mg — or a matching placebo, for 52 weeks. This describes what the trial administered; it is not a dosing recommendation. Tirzepatide is a prescription medicine, and any use is a clinical decision made with a licensed clinician.
Is the sleep apnea benefit just weight loss?
Excess weight is a recognized driver of obstructive sleep apnea, and in SURMOUNT-OSA tirzepatide reduced both the apnea-hypopnea index and body weight. The trial reports these as parallel clinical outcomes rather than proving that one caused the other, and it was not designed to isolate how much of the sleep-apnea improvement came specifically from weight loss versus other effects. The finding is best read as the observed result of the whole intervention.
What side effects were reported in SURMOUNT-OSA?
The most frequently reported adverse events with tirzepatide were gastrointestinal in nature and were mostly mild to moderate in severity, consistent with the known profile of the drug class. This page reports only the safety characterization stated in the peer-reviewed publication and does not assign rates to individual symptoms. Any decision about tolerability for a specific person belongs with a clinician.
Sources
This summary traces to the peer-reviewed publication and trial registration:
- Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA) — New England Journal of Medicine, 2024; PubMed 38912654.
- SURMOUNT-OSA (tirzepatide in obstructive sleep apnea and obesity) — ClinicalTrials.gov NCT05412004.
- Drug reference record: tirzepatide.