Relationship between components of metabolic syndrome and polysomnographic findings in obstructive sleep apnea

Obstructive sleep apnea/hypopnea syndrome (OSAHS) and metabolic syndrome are both growing health concerns, owing to the worldwide obesity epidemic. This study evaluates the potential association between the parameters of metabolic syndrome and OSAHS.

A total of 125 consecutive patients undergoing complete full night polysomnography were included. Insulin resistance (IR) was estimated using the homeostasis model assessment (HOMA), and metabolic syndrome was diagnosed according to the National Cholesterol Education Program (NCEP) criteria.

The prevalence of metabolic syndrome was 23.8% among patients with OSAHS. We found that IR, age, weight, hypertension, and metabolic syndrome prevalence increased significantly with severity of OSAHS. There were no differences between groups for lipid panels including total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C). Subjects with metabolic syndrome had significantly lowest desaturation value (76% vs. 81%) desaturation (76% vs. 81%, P = 0.003), lower mean nocturnal oxygen saturation (89.9% vs. 92.3%, P < 0.00.1), higher apnea-hypopnea index (AHI) (40.9 vs. 17, P < 0.001), and higher oxygen desaturation index (38 vs. 17, P = 0.002). Lowest desaturation and mean nocturnal oxygen saturation were significantly lower in subjects with IR (76% vs. 85%, P = 0.004 and 90.4% vs. 93.0%, P = 0.02). In multivariate analysis, the percent of time below 90% saturation [%T < 90]) (P = 0.04) was independently associated with IR.

Our results suggested that metabolic syndrome prevalence increased with severity of OSAHS and vice versa. Nocturnal hypoxic episodes in OSAHS patients could be a risk factor for developing hypertension and IR.