A total of 186 type 2 diabetic patients(DM group)and 72 healthy subjects(NDM group)were enrolled. Metabolic parameters and serum irisin levels were measured. The effects of intensity and time of the physical activity were evaluated. According to quartiles of plasma irisin levels,all subjects were divided into four groups and the prevalence of type 2 diabetes mellitus(T2DM) among four groups was compared. The relationship between plasma irisin level and physical activity in DM group was investigated. The results showed that plasma irisin levels were correlated negatively with the prevalence of T2DM(OR=0.984,95% CI 0.973~0.996);also negatively correlated with age(r=-0. 227, P=0. 029) and blood uric acid (r=-0. 225, P=0. 032) in the DM group. When corresponding exercise time was up to grade 4,the intensity of exercise would influence the irisin levels(χ2=7.319, P=0.025). After controlling for potential confounders such as age,metabolic parameters,intensity of work,timing of work,plasma irisin levels in DM group were correlated positively with the intensity of exercise (β=0.326, P=0.014) and negatively with corresponding exercise time(β=-0.454,P=0.001). These results suggest that the prevalence of T2DM decreases with the increase of plasma irisin level. Plasma irisin levels are increased after moderate intensity exercise(5~7 times weekly and 1h each time) or by short-term high-intensity exercise.