Obstructive sleep apnea and incident diabetes. A historical cohort study

Despite emerging evidence that obstructive sleep apnea (OSA) may cause metabolic disturbances independently of other known risk factors, it remains unclear whether OSA is associated with incident diabetes.

To evaluate whether risk of incident diabetes was related to the severity and physiologic consequences of OSA.

A historical cohort study was conducted using clinical and provincial health administrative data. All adults without previous diabetes referred with suspected OSA who underwent a diagnostic sleep study at St. Michael's Hospital (Toronto, Canada) between 1994 and 2010 were followed through health administrative data until May 2011 to examine the occurrence of diabetes. All OSA-related variables collected from the sleep study were examined as predictors in Cox regression models, controlling for sex, age, body mass index, smoking status, comorbidities, and income.

Over a median follow-up of 67 months, 1,017 (11.7%) of 8,678 patients developed diabetes, giving a cumulative incidence at 5 years of 9.1% (95% confidence interval, 8.4-9.8%). In fully adjusted models, patients with apnea-hypopnea index (AHI) greater than 30 had a 30% higher hazard of developing diabetes than those with AHI less than 5. Among other OSA-related variables, AHI in rapid eye movement sleep and time spent with oxygen saturation less than 90% were associated with incident diabetes, as were heart rate, neck circumference, and sleep time.

Among people with OSA, and controlling for multiple confounders, initial OSA severity and its physiologic consequences predicted subsequent risk for incident diabetes.