Objective: Obstructive sleep apnea syndrome (OSAS) often accompanies obesity and diabetes mellitus. This study was performed to investigate the prevalence of glucose intolerance and to determine independent predictors for insulin resistance in patients with OSAS.
Methods: A cross-sectional study of 679 OSAS patients with an apnea-hypopnea index (AHI)>or=5/h and 73 controls subjects (AHI<5/h) was done in a tertiary university-based medical center. They were assessed by nocturnal polysomnography and underwent an oral glucose tolerance test.
Results: The prevalence of diabetes mellitus in OSAS patients was higher than that of the control group (25.9% vs. 8.2%, p<0.001) and 424 patients (62.4%) received a new diagnosis of impaired glucose tolerance or diabetes mellitus. The very severe OSAS group (AHI >or=45/h) had significantly higher homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA beta-cell function than the other OSAS groups (AHI<45/h) and the control group. In a logistic regression model adjusting for potential confounders: age, AHI, minimum SpO(2) and body mass index (BMI), only BMI was associated with insulin resistance (HOMA-IR>3) (odds ratio: 1.272, 95% confidence interval 1.206-1.343, p<0.0001).
Conclusion: Glucose intolerance was more common in patients with OSAS. Insulin resistance was associated not with AHI but rather with BMI.