Objective: Obstructive sleep apnea syndrome (OSAS) is frequently complicated by metabolic syndrome, including diabetes and hypertension. Both OSAS and metabolic syndrome are strongly associated with obesity. Recently, adiponectin and leptin, which are secreted by adipose tissue, have been considered to play important roles in the progression of these diseases. Thus, to examine the association between leptin, adiponectin and OSAS, we measured the serum level of these adipocytokines in the same OSAS patients.
Methods and patients: Sixty-eight consecutive Japanese men, who recorded all-night polysomnography, were enrolled in this study, and were divided into three groups, control (n=15), moderate OSAS (n=21) and severe OSAS (n=32). We measured serum levels of adiponectin and leptin by ELISA.
Results: Serum leptin levels were positively correlated with apnea hypopnea index (AHI) (r=0.552, p<0.001), the percentage of time with less than 90% hemoglobin saturation level in total sleep time (%T<90) (r=0.399, p<0.001) and body mass index (BMI) (r=0.807, p<0.0001). These parameters were suggested as the determinant factor for the serum leptin level by stepwise multiple regression analysis. On the other hand, serum adiponectin levels showed a positive correlation with age (r=0.361, p=0.005) and HDL-cholesterol level (r=0.274, p=0.039). Although there was no significant correlation between serum adiponectin levels and AHI or %T<90, serum adiponectin levels were chosen at a determinant factor of %T<90.
Conclusion: These results suggested that the increasing severity of OSAS induces an increase in setum leptin concentration, but the serum adiponectin levels may be regulated independently of the degree of OSAS, obesity and serum leptin levels in patients with OSAS.