Obstructive sleep apnoea (OSA)

Research context

Obstructive sleep apnoea affects an estimated 1.5 million UK adults, with fewer than ~30% of clinically significant cases formally diagnosed and treated; CPAP is the gold standard but adherence is modest (~50% at 12 months), creating a large unmet need. SURMOUNT-OSA (tirzepatide, 2024) was the first designed-for-purpose pharmacological OSA phase 3 trial: a 52-week study in adults with moderate-to-severe OSA (AHI ≥15) and obesity, in two parallel cohorts (non-CPAP and CPAP-using). At week 52 tirzepatide 15 mg reduced AHI by a mean of ~27.4 events/hour (−55% from baseline) in the non-CPAP cohort and ~29.3 events/hour (−62.8%) in the CPAP cohort, versus small placebo changes, with a substantial proportion achieving OSA resolution (AHI <5). This led to a US FDA label expansion.

Why this matters metabolically

OSA in obesity arises from peripharyngeal fat deposition narrowing the airway, reduced lung volumes impairing dilator-muscle traction, and adiposity-related changes in ventilatory control and inflammation — all of which weight reduction addresses, producing AHI improvements that range from modest to full resolution with sufficient weight loss. Tirzepatide, with the deepest weight reduction of any licensed agent, was the natural OSA candidate; emerging data also raise the possibility of direct GLP-1/GIP effects on upper-airway muscle or respiratory control independent of weight. AHI reduction is additionally linked to cardiometabolic outcomes including blood pressure and arrhythmia risk.

FAQs

What are the SURMOUNT-OSA trial results for tirzepatide?

SURMOUNT-OSA was a phase 3 RCT with two parallel cohorts (CPAP users and non-CPAP users). At 52 weeks, tirzepatide 15 mg achieved a mean AHI reduction of roughly 27–30 events per hour, and approximately 42–50% of participants in the tirzepatide arms achieved OSA resolution (AHI <5 events per hour) compared with approximately 16% on placebo.

Is the OSA benefit from tirzepatide entirely explained by weight loss?

The mechanistic attribution remains debated. Regression analyses suggest weight reduction accounts for a substantial — but potentially not complete — proportion of the AHI improvement. Whether GLP-1/GIP receptor effects on upper-airway muscle or neural control contribute independently of weight remains to be tested in an adequately powered, weight-controlled design.

Does this mean tirzepatide is a CPAP replacement?

No. SURMOUNT-OSA is not a CPAP-replacement trial. CPAP remains first-line for moderate-to-severe OSA. The findings suggest tirzepatide may be a useful adjunct in obese individuals — reducing CPAP dependence or enabling AHI reduction in those unable to tolerate CPAP. Tirzepatide is not MHRA-licensed with an OSA indication in the UK.

How is AHI measured and what counts as clinically meaningful improvement?

The apnoea-hypopnoea index (AHI) is the number of apnoea and hypopnoea events per hour of sleep, measured by polysomnography or portable monitoring. Mild OSA is AHI 5–14.9; moderate 15–29.9; severe ≥30. A clinically meaningful improvement is generally a reduction of ≥10–15 events per hour or movement to a lower severity category; OSA resolution is AHI <5.

What is the UK regulatory status of tirzepatide for OSA?

As of mid-2026, tirzepatide does not hold a specific MHRA licence for OSA. It is licensed for T2D (Mounjaro) and chronic weight management in adults with obesity or overweight with comorbidities; OSA is a weight-related comorbidity that may qualify patients under existing weight-management licensing, but specific OSA claims require a dedicated indication approval.