The purpose of this study was to examine the associations of carotid artery intima-media wall thickness (IMT) with hemostatic proteins and cardiovascular risk factors (CVRFs) in participants with and without non-insulin dependent diabetes mellitus (NIDDM). IMT measurements were determined by high resolution B-mode ultrasound imaging of the carotid arteries in 921 participants with NIDDM and 11,964 non-diabetic participants aged 45-64 years. Fasting glucose, serum lipids and activated partial thromboplastin time, factor VIII fibrinogen, factor VII, antithrombin III, protein C, and von Willebrand factor measurements were made. Compared to non-diabetic participants, participants with NIDDM had a more adverse pattern of CVRFs and a more procoagulatory profile. Participants with NIDDM had 0.06 mm (8.1%) higher mean IMT compared to non-diabetic participants after adjusting for age and gender (P < 0.001). However, only plasma fibrinogen concentrations showed statistically significant positive associations with IMT in both groups. After adjusting for CVRFs and fibrinogen, mean IMT remained 0.04 mm (5.4%) higher in diabetic compared to non-diabetic participants. Despite the more procoagulatory profile in participants with NIDDM, only plasma fibrinogen concentrations were independently associated with mean IMT. The association of NIDDM with mean IMT was only partly explained by CVRFs.