The main finding
In one sentence: In two 52-week trials of adults with obesity and moderate-to-severe sleep apnea, tirzepatide lowered systolic blood pressure at 48 weeks by 7.9 mmHg more than placebo in people not using a breathing machine and by 4.3 mmHg more in people using one.
Group averages, not an individual prediction. A trial result describes what happened to a defined group over a defined time.
On this page
Why this study matters
Obstructive sleep apnea, or OSA, is a condition in which the airway repeatedly closes during sleep. It is closely linked to a higher body weight and to high blood pressure and other heart risks. SURMOUNT-OSA tested tirzepatide (Zepbound, Mounjaro) in people with both OSA and obesity. This paper reports the planned secondary outcomes on blood pressure and other heart and metabolic measures. It matters because it shows what happened to risk factors beyond weight and breathing events in this group.
Who was in the study
The two trials enrolled 469 adults living with obesity and moderate-to-severe OSA. Study 1 enrolled 234 people who were not using positive airway pressure, or PAP. PAP is a machine worn at night that blows air to keep the airway open. Study 2 enrolled 235 people who were using PAP. Each trial ran for 52 weeks, and blood pressure was assessed at 48 weeks.
What the researchers did
SURMOUNT-OSA was a master protocol containing two 52-week, randomized, double-blind, placebo-controlled phase 3 studies. Randomized means people were assigned by chance. Double-blind means neither participants nor researchers knew who received which treatment. A placebo is an injection that looks the same but has no medicine in it. Within each study, people received weekly tirzepatide at their maximum tolerated dose of 10 or 15 mg, or placebo.
The parent trial's primary outcome was the apnea-hypopnea index, a count of breathing interruptions per hour of sleep. This paper reports prespecified secondary outcomes, meaning outcomes the researchers planned to measure before the trial began: changes in blood pressure, blood fats, inflammation and fasting insulin. The analysis used an efficacy estimand, which counts data collected before anyone permanently stopped treatment, with missing values filled in by multiple imputation. An estimand is a precise statement of what a trial measures and how it handles missing data. The paper also contains post hoc analyses that were not planned in advance; we did not use them.
What they found
At 48 weeks, systolic blood pressure, the top number in a reading, changed as follows (R32-C59):
| Study | Tirzepatide | Placebo | Difference (95% CI) |
|---|---|---|---|
| Study 1 (not using PAP) | -9.6 mmHg | -1.7 mmHg | -7.9 mmHg (-11.0 to -4.9) |
| Study 2 (using PAP) | -7.6 mmHg | -3.3 mmHg | -4.3 mmHg (-7.3 to -1.2) |
A confidence interval, or CI, is the range within which the true difference most likely sits. In both studies, the interval sits entirely below zero, which means the blood pressure reduction with tirzepatide was larger than with placebo.
The abstract states that in both studies tirzepatide was associated with greater improvement in cardiometabolic risk factors than placebo, but the summary we reviewed does not give figures for the other prespecified measures, such as blood fats, inflammation and fasting insulin. It also does not give weight change or breathing results, which belong to the parent paper.
Side effects and people who stopped
The published summary we reviewed does not report adverse events, the number of people who stopped treatment, or the number who stopped because of side effects. Those results are in the main SURMOUNT-OSA paper, which we did not use because it carries a published correction.
What this study does not tell you
- Blood pressure, blood fats and similar measures are surrogate outcomes. They are markers of risk, not heart attacks or strokes. This was not a cardiovascular outcomes trial.
- The main SURMOUNT-OSA paper has a published correction, so this page does not report the breathing or weight results from it.
- The paper includes post hoc mediation analyses about whether weight loss or breathing changes explain the results. These were not planned in advance and are not summarized here.
- No adjustment for multiple comparisons was made for exploratory endpoints, and the efficacy estimand counts only data collected while people stayed on treatment, which can make results look better than they would in everyday use.
- Everyone had obesity and moderate-to-severe OSA. The results do not describe people with milder sleep apnea or a lower BMI.
- The funding statement and author disclosures were not included in the text we reviewed.
What it means in Canada
For Canadian readers with sleep apnea and a higher body weight, this paper adds detail on how tirzepatide changed blood pressure in that group over 48 weeks. It does not describe how the medicine is prescribed or paid for here, and it does not replace sleep apnea treatment decisions made with a clinician. See tirzepatide in Canada, public drug coverage by province and compare services.
Common questions
How much did tirzepatide lower blood pressure in SURMOUNT-OSA?
At 48 weeks, systolic blood pressure fell 7.9 mmHg more than placebo in the study without PAP (95% CI -11.0 to -4.9) and 4.3 mmHg more in the study with PAP (95% CI -7.3 to -1.2).
What is PAP in the SURMOUNT-OSA trial?
PAP means positive airway pressure, a machine worn at night to keep the airway open. Study 1 enrolled people not using PAP and study 2 enrolled people using it.
Is this the main SURMOUNT-OSA results paper?
No. This paper reports planned secondary outcomes on heart and metabolic risk. The main results paper has a published correction, so our review did not use it.
Related reading
Other studies in this library that bear on the same question.
SCALE Sleep Apnea: liraglutide
Tirzepatide for weight loss in adults without diabetes: SURMOUNT-1
Tirzepatide for heart failure with a higher body weight: SUMMIT
Cochrane review of tirzepatide for adults with obesity
What happens to weight when tirzepatide is stopped: SURMOUNT-4
Source
Original paper: Atul Malhotra, SURMOUNT-OSA prespecified cardiometabolic secondary outcomes, Nature medicine, 2026. PubMed: https://pubmed.ncbi.nlm.nih.gov/41540105/. DOI: https://doi.org/10.1038/s41591-025-04071-1. Funding: The summary we reviewed does not state the funding source. How we summarized it: full text and extracted data.
This page explains a published study. It is not medical advice and does not describe whether a medicine is right for you. Talk to your doctor, nurse practitioner or pharmacist about your own situation. Reviewed and signed by two pharmacists registered in British Columbia, 2026-09-18.
Evidence records behind this page
Each record is a row in the clinical evidence file, taken from the published paper named above. The caution column is the limit the researcher recorded for that number.
This table scrolls sideways.
| Record | What the paper reports | Type | Population | Caution | Source |
|---|---|---|---|---|---|
| R32-C59 | In the prespecified SURMOUNT-OSA analysis, tirzepatide reduced systolic blood pressure more than placebo at 48 weeks: by 7.9 mmHg in the trial without positive airway pressure (PAP) and 4.3 mmHg in the trial using PAP. | direct evidence | Adults with obesity and moderate-to-severe OSA; study 1 not using PAP, study 2 using PAP | Surrogate cardiometabolic endpoints; not a cardiovascular-outcomes trial. Parent primary OSA paper excluded for correction. Only prespecified outcomes used here; post hoc mediation omitted. Body extraction excludes linked disclosures/supplements. | PubMed 41540105 |