Hypertension (HT) is frequently associated with diabetes mellitus (DM) and its prevalence doubles in diabetics compared to the general population. This high prevalence is associated with increased stiffness of large arteries, which often precedes macrovascular events. The aim of our study was to evaluate the influence of HT and type II DM on aortic stiffness in patients with one disease or the other compared to those with both HT and type II DM. We studied 220 patients, 50 with type II DM (Group A), 50 with HT (Group B), 85 with both diseases (Group C), and 35 healthy subjects (HS). Regional arterial stiffness was assessed by automatic measurement of the carotid-femoral pulse wave velocity (PWV). For each patient, we evaluated: age, sex, body mass index, smoking habit, heart rate, SBP/DBP, pulse pressure (PP), mean BP, fasting glucose, lipid profile, uric acid, and fibrinogen. Group C had significantly more women and non smokers and the highest PP (61+/-14 mmHg). Of biochemical parameters, only fibrinogen was higher in Group A and in Group C (P<0.01 and P<0.001, respectively). Group C had a significantly higher PWV than the other four groups (P<0.0001). Stepwise forward regression analysis showed that fasting glucose was the first independent determinant of PWV (P<0.0001). In conclusion, this study shows that patients with DM and HT have higher arterial stiffness compared to HS and those with one disease or the other. Fasting glucose is the major independent determinant of PWV, which may be used as a relevant tool to assess the influence of cardiovascular risk factors on arterial stiffness in high-risk patients.