Obstructive sleep apnea syndrome(OSAS)is a sleep disorder disease,which is usually characterized by sudden pauses of breathing during sleep and interruption of sleep rhythm.The pathological mechanism of OSAS is closely related to many metabolic diseases including type 2 diabetes mellitus(T2DM),insulin resistance,nonalcohol-ic fatty liver disease(NAFLD)and obesity.Metabolic diseases are involved in the occurrence and development of OSAS.Fully understanding the association among T2DM,hypertension,NAFLD,obesity and OSAS is of great sig-nificance for the clinical diagnosis and treatment of OSAS.