Type 2 diabetes mellitus (DM2) and high blood pressure (HBP) may contribute to the development of cardiovascular disease, and inflammation may be an important factor in these diseases. In the present study, plasma levels of high-sensitivity C-reactive protein (hs-CRP) were measured in subjects with DM2 and/or HBP and compared to those of normal subjects. Eighty-nine subjects were analyzed for hs-CRP, including 13 normotensive patients with DM2, 17 patients with HBP, 34 hypertensive patients with DM2 (DM2+HBP) and 25 normal subjects. The plasma hs-CRP levels were significantly lower in the controls than in the HBP+DM2 group (p < 0.05). DM2 associated with HBP was also correlated with increased plasma hs-CRP levels (n = 89, r = 0.25, p = 0.0162). Only hypertensive patients with DM2 had higher levels of hs-CRP, a circulating inflammatory marker, than normal subjects. This finding suggests that patients with two associated diseases have a more active inflammatory state.