Prevalence and recognition of obstructive sleep apnea in Chinese patients with type 2 diabetes mellitus.

Background: Obstructive sleep apnea (OSA) is associated with disorders of glucose metabolism. Previous studies revealed a high prevalence of OSA among subjects with type 2 diabetes mellitus (DM). The aims of this study were to determine the prevalence of OSA and associated clinical factors in Chinese patients with DM.

Methods: All records of the DM clinic at a teaching hospital in Hong Kong were screened between January 2007 and June 2008. Inclusion criteria for patients were Chinese, aged 18 to 75 years, with type 2 DM. Patients with unstable medical illnesses, gestational diabetes, or on renal replacement therapy were excluded.

Results: Of 3,489 records screened, 1,859 subjects were eligible. A random sample of 663 (mean age, 58.2 ± 10.8; mean BMI, 26.0 ± 4.6), except six with known OSA, were invited for polysomnography (PSG). Of 165 subjects on which PSG was performed, OSA was diagnosed (apnea-hypopnea index [AHI] ≥ 5.0/h) in 89 subjects (53.9%, median Epworth Sleepiness Scale, 6 [interquartile range 3, 10]). Fifty-four (32.7%) had moderate/severe OSA (AHI ≥ 15/h). The estimated OSA prevalence in this diabetic cohort was 17.5% (24.7% in men, 10.3% in women). Regression analysis identified that AHI was associated independently with higher BMI, advanced age, male sex, and higher diastolic BP (R(2) = 29.6%). The adjusted OR of requiring three or more antihypertensive drugs in moderate/severe OSA was 2.48 (95% CI, 1.05-5.87). No association between glycemic control (HbA1c) and sleep was identified.

Conclusions: In conclusion, OSA is more prevalent in Chinese adults with DM than in the general population. A high index of suspicion for OSA in patients with DM is warranted, because they may not have overt daytime sleepiness.