2010 Oct - Prevalence and recognition of obstructive sleep apnea in Chinese with type 2 diabetes mellitus
Dr Lui Mei Sze, Queen Mary Hospital
Obstructive sleep apnea is associated with disorders of glucose metabolism. Previous studies revealed high prevalence of OSA among Caucasian subjects with type 2 diabetes mellitus (DM). The aims of this study were to find out the prevalence of OSA and its clinical predictors in Chinese patients with DM.
All records of the Diabetic Clinic at a teaching hospital were screened between January 2007 and June 2008. Inclusion criteria were Chinese, age 18–75 years and type 2 DM. Patients with unstable medical illnesses, gestational diabetes or on renal replacement therapy were excluded.
Of 3489 records screened, 1859 subjects were eligible. A random sample of 663 was drawn (mean age 58.2, mean BMI 26.0), of whom six had known OSA, and were invited to undergo polysomnography. Of the 165 subjects with PSG performed, OSA was diagnosed (AHI ≥ 5.0/hr) in 89 subjects (53.9%). Median Epworth Sleepiness Scale was 6. Fifty-three (32.1%) had moderate-severe OSA (AHI ≧ 15/hr). The conservative OSA prevalence estimate among the random sample of diabetic subjects was 14.3% (95% CI 11.6%, 17.1%). Multivariate linear regression identified higher BMI, advanced age, male gender and higher diastolic blood pressure (DBP) as independent predictors of AHI (R2=29.6%). The adjusted odds ratio of requiring three or more antihypertensive drugs in moderate OSA was 2.48 (95% CI 1.05 - 5.87). However, no correlation with glycemic control was identified.
OSA is more prevalent in Chinese adults with DM than the general population. A high index of suspicion for OSA in DM patients is warranted since they may not have overt daytime sleepiness. Higher BMI, advanced age, male gender and higher DBP are the clinical predictors of severity.