Risk of mortality among patients with moderate to severe obstructive sleep apnea and diabetes mellitus: results from the SantOSA cohort.

Introduction: Patients with obstructive sleep apnea (OSA) and comorbid diabetes mellitus (DM) are reported to have an increased risk of cardiovascular (CV) outcomes; however, data on CV mortality are scant.

Aim: This study aimed to evaluate if patients with comorbid OSA and DM have an increased risk of CV mortality that is higher than the two diseases in isolation.

Methods: In this prospective cohort study, we included patients referred for a sleep study with and without DM at baseline. We developed four study groups as follows: group 1 (reference group), OSA (-) DM (-); group 2, OSA (-) DM (+); group 3, OSA (+) DM (-); group 4, OSA (+) DM (+). Intergroup differences were evaluated using the t test and χ test, and multivariate analysis was performed using logistic regression. The incidence rates of CV mortality were calculated using the Kaplan-Meier (log-rank) model, and adjusted HRs were calculated using the Cox regression model.

Results: A total of 1447 patients were included in the analysis-group 1: 441 participants; group 2: 141 participants; group 3: 736 participants; group 4: 151 participants. The mean follow-up was 5 years. The association between OSA + DM showed an independent risk of incident CV mortality (HR 2.37, CI 1.16-4.82, p = 0.02) and an increased prevalence of coronary heart disease (OR 3.44, CI 1.73-5.59, p < 0.01). In addition, T90% was also associated with CV mortality.

Conclusion: The coexistence of OSA + DM was associated with an independent risk of CV mortality. In addition, T90% was also associated with CV mortality.