Considerable research has been done on factors that influence the development of Type II (non-insulindependent) diabetes mellitus. Age, family history of diabetes, obesity, alcohol consumption, cigarette smoking, reduced physical activity, hypertension and dyslipidaemia have been confirmed as important predictors of Type II diabetes mellitus [1±11]. More recently, markers of low-grade inflammation have been shown to predict the occurrence of Type II diabetes mellitus [12,13]. Concentrations of inflammatory markers and mediators of inflammation ± cytokines such as tumor necrosis factor (TNF)-a and interleukin (IL)-6 ± are higher in patients with Type II diabetes mellitus, particularly in those with features of insulin resistance [14±16]. White blood cells (WBCs), another major component of the inflammatory process, are increased by cytokines, especially Diabetologia (2002) Abstract Aims/hypothesis. To investigate the association between white blood-cell (WBC) count and the development of diabetes, independent of cigarette smoking. Methods. We examined 2953 Japanese men who were office workers and between 35 and 59 years of age and who did not have impaired fasting glucose (IFG) (a fasting glucose concentration of 6.1±6.9 mmol/l), Type II (non-insulin-dependent) diabetes mellitus (a fasting glucose concentration of ³ 7.0 mmol/l or more or receipt of hypoglycaemic medication), medication for hypertension, and a history of cardiovascular disease. Fasting glucose concentrations were measured at annual health examinations from May 1994 through May 2000. Results. After controlling for potential predictors of diabetes, the relative risk for IFG or Type II diabetes mellitus compared with a WBC count of less than 5.3´10 9 cells/l was 1.2 (95 %-CI, 0.6±2.3), 1.6 (CI, 0.8±3