Our objective was to evaluate whether selected hemostasis variables, some of which may reflect inflammation or endothelial dysfunction, are independently associated with the development of diabetes. We studied a biethnic cohort of 12,330 men and women, 45-64 years of age, of the Atherosclerosis Risk in Communities Study. New cases of diabetes were diagnosed by a reported physician diagnosis, hypoglycemic medication use, or a casual or fasting serum glucose level of > or = 11.1 or > or = 7 mmol/l, respectively. Over an average follow-up of 7 years, 1,335 new cases of diabetes were detected. The odds ratios (4th versus 1st quartile) of developing diabetes, adjusted by logistic regression for age, sex, race, study center, family history of diabetes, fasting glucose, physical activity, and smoking, were 1.2 (95% CI 1.0-1.5) for fibrinogen and 1.4 (1.1-1.6) for factor VII. Associations for factor VIII, von Willebrand factor, and activated partial thromboplastin time were found to be 1.8 (1.3-2.3), 1.4 (1.1-1.8), and 0.63 (0.49-0.82), respectively, in women. Although further adjustment for BMI and waist-to-hip ratio diminished the relationships, a highly statistically significant association (P = 0.001) remained for factor VIII (1.6 [1.2-2.1]) in women. Factor VIII and other hemostasis variables are associated with the development of diabetes in middle-aged adults. These findings support a role for inflammation and, particularly in women, endothelial dysfunction in the pathogenesis of type 2 diabetes.