Obstructive sleep apnoea (OSA) is a highly prevalent condition but studies exploring the burden of OSA-associated comorbidities have been limited by small sample sizes with underrepresentation of women.We queried the Truven Health MarketScan Research Databases 2003-2012, which is a collection of health insurance claims for working adults and retirees with employer-sponsored health insurance. Adults with a diagnostic code for OSA with at least 12 months of follow-up from the index date of OSA diagnosis were compared to a matched random sample. Comorbidities were assessed using International Classification of Diseases, Ninth Edition, codes. A logistic regression model was constructed to test the independent association between OSA and comorbidities.Our cohort included 1,704,905 patients with OSA and 1,704,417 matched controls. All comorbidities were significantly more prevalent in OSA patients. Type 2 diabetes and ischaemic heart disease were more prevalent in men but hypertension and depression were more prevalent in women with OSA. In contrast, the sex differences in the prevalence of congestive heart failure, arrhythmias and stroke were less pronounced. The prevalence of comorbidities increased with age but the effect of age varied based on the specific comorbidity. The divergence between OSA and controls was more pronounced after the sixth decade of life for most cardiovascular diseases (i.e.heart failure, ischaemic heart disease, stroke and arrhythmias), while depression exhibited an opposite trend. In a fully adjusted model, the odds of all comorbidities were significantly increased in OSA patients.In a large, nationally representative sample of working and retired people, OSA is strongly associated with significant comorbidities in both men and women with unique sex differences emerging.