BACKGOUND: Type 2 diabetes and metabolic syndrome are associated with an increased risk of cardiovascular disease, and inflammation is also closely associated with cardiovascular disease. The white blood cell count, which is a marker of systemic inflammation, has been found to correlated with the risk of cardiovascular disease. The aim of this study was to evaluate the association between metabolic syndrome and the WBC count in type 2 diabetic patients. METHODS: 606 patients (males 318, females 288, BMI 25.6+/-3.2 kg/m2 and duration of diabetes 4.8+/-5.9year) were enrolled. The WBC and differential counts, anthropometry, blood pressure, fasting glucose, insulin and lipid profiles were measured. RESULTS: According to the quartiles of the WBC count, the number of components of metabolic syndrome and percentage of patients with metabolic syndrome were increased in the highest WBC count quartile. The WBC, neutrophil, lymphocyte, monocyte and eosinophil counts increased with increasing number of components of metabolic syndrome, but not that of the basophil count. The WBC, neutrophil, lymphocyte, monocyte and eosinophil counts were higher in patients with metabolic syndrome than in those without. The WBC count was found to be positively correlated with the waist circumference(gamma=0.090), systolic blood pressure(gamma=0.090), diastolic blood pressure(gamma=0.104), triglyceride(gamma=0.252), insulin(gamma=0.168) and HOMAIR(gamma=0.170), but negatively with high-density lipoprotein cholesterol(gamma= -0.167)(P<0.05, respectively). CONCLUSION: Chronic inflammation, as indicated by a higher than normal WBC count, may increased with the increasing number of components of metabolic syndrome.