Obstructive sleep apnea and incident diabetes: a historical cohort study

Rationale — 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.

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

Methods and Measurements — A historical cohort study was conducted using a 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.

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

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