Mounjaro and Sleep Apnoea: What the Trial Data Shows

Mounjaro and sleep apnoea are more closely connected than many patients realise. Obstructive sleep apnoea (OSA) affects an estimated 1.5 million adults in the UK, and excess weight is the single strongest modifiable risk factor. The condition causes repeated pauses in breathing during sleep, leaving patients exhausted, raising blood pressure and increasing the risk of stroke and heart attack.

For years the standard treatments have been CPAP machines, lifestyle changes and, in some cases, surgery. Now a landmark clinical trial has shown that tirzepatide, the active ingredient in Mounjaro, can dramatically reduce sleep apnoea severity. In this article we look at what the evidence actually shows, who may benefit and what it means for CutKilo patients already on treatment.

Yes. The SURMOUNT-OSA trial, published in the New England Journal of Medicine in 2024, found that tirzepatide reduced the severity of obstructive sleep apnoea by up to 62.8% compared with placebo. More than half of participants on the highest dose met the clinical criteria for disease resolution. These improvements were driven primarily by significant weight loss and reductions in visceral fat, both of which relieve the mechanical obstruction of the upper airway that causes OSA.

Obstructive sleep apnoea occurs when the muscles in the throat relax excessively during sleep, causing the airway to narrow or close completely. Each episode, called an apnoea or hypopnoea, can last from a few seconds to over a minute and may happen dozens or even hundreds of times per night.

Severity is measured using the apnoea-hypopnoea index (AHI), which counts the number of breathing disruptions per hour of sleep. An AHI of 5 to 14 is classified as mild, 15 to 29 as moderate and 30 or above as severe. Common symptoms include loud snoring, witnessed breathing pauses, waking with a dry mouth or headache, excessive daytime sleepiness and difficulty concentrating.

OSA is strongly associated with obesity. Fat deposits around the neck and upper airway increase the mechanical load on the throat, while visceral fat around the abdomen pushes the diaphragm upward and reduces lung volume. NICE estimates that around 60% to 90% of adults with OSA are overweight or obese, making weight management a cornerstone of treatment alongside CPAP therapy.

The SURMOUNT-OSA programme consisted of two randomised, double-blind, placebo-controlled phase 3 trials enrolling adults with moderate to severe obstructive sleep apnoea and a BMI of 30 or above. Trial 1 included participants not using CPAP, while Trial 2 enrolled those already on CPAP who could not tolerate it or wished to discontinue. Participants received tirzepatide (up to 15 mg weekly) or placebo for 52 weeks.

The results, published in the New England Journal of Medicine (Malhotra et al., 2024, DOI: 10.1056/NEJMoa2404881), were striking. In Trial 1, tirzepatide reduced AHI by a mean of 25.3 events per hour compared with 5.3 for placebo. In Trial 2, the reductions were 29.3 versus 5.5. That translates to roughly a 55% to 63% reduction in airway obstruction events per hour.

Crucially, 43% to 52% of participants on tirzepatide met the prespecified criteria for disease resolution, defined as an AHI below 5 combined with an Epworth Sleepiness Scale score below 11. By comparison, only 14% to 16% of those on placebo achieved the same threshold. Participants also experienced significant improvements in oxygen saturation, systolic blood pressure, high-sensitivity C-reactive protein (a marker of systemic inflammation) and patient-reported sleep quality.

The relationship between weight and OSA is well established. A 10% reduction in body weight has been shown to produce approximately a 26% reduction in AHI in observational studies. With tirzepatide, SURMOUNT-OSA participants lost a mean of 18% to 20% of their body weight over 52 weeks, far exceeding the thresholds typically needed to see meaningful airway improvement.

Weight loss helps OSA through several mechanisms. Reducing fat around the pharynx and tongue base directly widens the airway. Lowering abdominal and visceral fat relieves pressure on the diaphragm, improving lung volumes and the stability of the upper airway during sleep. Reductions in systemic inflammation may also decrease fluid retention in the neck tissues, further opening the airway. If you are tracking your progress on Mounjaro, DEXA London, CutKilo’s sister service at the same 86 Harley Street clinic, offers body composition scanning that can show exactly where you are losing fat, including visceral fat around the organs.

These combined effects explain why the improvements seen with tirzepatide were so pronounced. It is not simply that patients weighed less; the pattern of fat loss, particularly the reduction in visceral and upper-body fat, appears to be especially beneficial for airway function.

Tirzepatide is not currently licensed in the UK specifically for the treatment of sleep apnoea. Its MHRA-approved indication remains the management of obesity and type 2 diabetes. However, many CutKilo patients who start treatment for weight loss find that their sleep quality improves significantly as a secondary benefit.

If you have been diagnosed with moderate to severe OSA and have a BMI of 30 or above, the trial data suggests that treatment with tirzepatide could meaningfully reduce your AHI alongside weight loss. Patients who struggle with CPAP adherence may find this particularly relevant, as the SURMOUNT-OSA Trial 2 specifically enrolled people who had difficulty tolerating their CPAP device.

It is important to note that Mounjaro should not replace CPAP without medical supervision. CutKilo’s prescribing doctors will discuss your sleep history during your consultation and, where appropriate, liaise with your sleep clinic or GP to ensure a coordinated approach to treatment.

If you are already taking Mounjaro through CutKilo and have noticed improvements in your sleep, snoring or daytime energy levels, you are likely experiencing the same physiological benefits documented in the SURMOUNT-OSA trial. Many patients report that their partner first notices the change: less snoring, fewer breathing pauses and a quieter night overall.

If you suspect you may have undiagnosed sleep apnoea, common warning signs include persistent loud snoring, feeling unrefreshed after a full night of sleep, morning headaches and excessive daytime drowsiness. Your CutKilo doctor can help you decide whether a formal sleep study is appropriate and refer you to a specialist if needed.

Mounjaro also provides cardiovascular benefits beyond sleep apnoea improvement. Research has shown that tirzepatide can reduce blood pressure, improve lipid profiles and lower markers of inflammation. You can read more about these findings in our guide to Mounjaro and heart health, which covers the wider cardiovascular evidence.

One important consideration is whether the improvements in sleep apnoea persist after stopping treatment. The SURMOUNT-OSA trial measured outcomes at 52 weeks while participants were still on tirzepatide, so long-term maintenance data after discontinuation is still being gathered.

What we know from broader obesity research is that weight regain after stopping GLP-1 receptor agonist therapy is common, and if weight returns, OSA severity is likely to worsen again. This underscores the importance of a structured approach to treatment duration. At CutKilo, our doctors work with patients on a personalised tapering plan, ensuring that lifestyle changes in diet, exercise and sleep hygiene are well established before considering any reduction in dose.

Maintaining adequate protein intake on Mounjaro is also relevant here. Preserving lean muscle mass during weight loss helps sustain a higher metabolic rate and supports the kind of body composition changes that keep OSA in remission.

The SURMOUNT-OSA trial represents the strongest evidence to date that a weight-loss medication can meaningfully treat obstructive sleep apnoea. With up to 63% reductions in AHI and disease resolution in over half of participants, tirzepatide offers a genuinely new option for patients whose sleep apnoea is driven by excess weight. If you are on Mounjaro through CutKilo, the improvements in your sleep may be one of the most important benefits of treatment, reducing not just daytime tiredness but also the long-term cardiovascular risks associated with untreated OSA.

Can Mounjaro cure sleep apnoea? The SURMOUNT-OSA trial showed that over half of participants on tirzepatide met the criteria for disease resolution after 52 weeks. However, this depends on maintaining the weight loss. If weight is regained after stopping treatment, OSA is likely to return. The term “resolution” in the trial refers to an AHI below 5 with normal daytime sleepiness scores, which is effectively the clinical threshold for no longer having the condition.

How quickly does sleep apnoea improve on Mounjaro? The trial measured outcomes at 52 weeks, so the full extent of improvement was seen over that period. Anecdotally, many patients report improvements in snoring and sleep quality within the first 8 to 12 weeks of treatment, as initial weight loss begins to relieve airway obstruction.

Can I stop using my CPAP machine if I start Mounjaro? You should not stop using your CPAP without discussing it with your sleep specialist or GP. While the evidence for tirzepatide is encouraging, any changes to your CPAP regimen should be guided by repeat sleep studies showing improvement in your AHI.

Is Mounjaro prescribed specifically for sleep apnoea in the UK? Not currently. Tirzepatide is licensed by the MHRA for weight management in adults with a BMI of 30 or above (or 27 with a weight-related comorbidity) and for type 2 diabetes. However, improvement in OSA is a recognised secondary benefit of the weight loss it produces. CutKilo prescribes Mounjaro for weight management, and sleep apnoea improvement may occur as part of that treatment.

Does sleep apnoea affect weight loss on Mounjaro? Untreated OSA can make weight loss harder. Poor sleep quality disrupts hormones that regulate appetite, including leptin and ghrelin, often increasing hunger and cravings. Treating OSA alongside weight-loss medication may therefore create a positive cycle: better sleep supports greater weight loss, which in turn further improves sleep apnoea.