Adipocyte fatty acid binding protein (A-FABP) is a member of the FABP super family, is abundant in adipocytes and macrophages. Regulatory functions of A-FABP in lipid and glucose metabolism have been described, and it is suggested to play an important role in the pathogenesis of metabolic syndrome.We hypothesize that obstructive sleep apnea (OSA) may upregulate A-FABP production and thus causally contribute to metabolic dysfunction. Our group has recently demonstrated that A-FABP, expressed and secreted from adipocytes, is present in the blood stream .The levels of A-FABP correlated with various metabolic variates in the metabolic syndrome. Furthermore, we have obtained novel data in men with a range of sleep disordered breathing showed that the duration of oxygen desaturation correlated with circulating levels of A-FABP, independent of age and waist/body mass index. The current proposal aims to pursue this finding and further explore the role of A-FABP in the association of OSA and metabolic dysfunction.