We observed the changes of parameters of coagulation and fibrinolytic system in order to understand the clinical implication of these variations in type II diabetic patients. Subjects consisted of 22 patients with type II diabetes mellitus and 25 healthy controls. Compared with the control, activated partial thromboplastin time, prothrombin time were shortened in the patients. The diabetic subjects also displayed higher levels of D-dimer, serum fibrin degradation products, median concentrations of fibrinogen (3.99 vs 2.96 g/L, P < 0.01) and von Willebrand factor (149% vs 87%, P < 0.01). Levels of antithrombin III activity or antigen were not different from control values. Simple linear regression analysis revealed a negative correlation between antithrombin III activity and fast blood glucose. Diabetic patients with vascular complications had significantly higher levels of fibrinogen and D-dimer than those without diabetic angiopathy. Our data demonstrated that patients with type II diabetes mellitus had a hypercoagulable state. We believed the activation of coagulation might contribute to the vascular complications in diabetics.