Type II diabetes is an hemorheological disease in which hyperglycemia increases the shear stress contributing to inflammation and dysfunction of endothelium. The purpose of this study was to identify the relationship between serum C-reactive protein and glucose levels in noncontrolled type II diabetic subjects. A cross-sectional study was conducted, including 62 noncontrolled type II diabetic subjects that were assigned to two groups. One group was patients with acute diarrhea or urinary tract infection and the other group was diabetic subjects who were infectious-disease free. Sixty-two subjects without diabetes constituted the respective control groups. Heart failure, other acute febrile illnesses, asymptomatic infection, renal, hepatic, malignant or chronic inflammatory illness, and macrovascular disease were considered as exclusion criteria. Laboratory measurements were performed. Thirty (96.7%) and 29 (93.5%) diabetic patients in the groups with and without infectious disease, and 28 (90.3%) control subjects with infectious disease had elevated C-reactive protein levels (> or =10 mg/L). In contrast, healthy control subjects did not have elevated serum C-reactive protein levels. Multiple regression analysis showed a significant association between C-reactive protein levels and hyperglycemia (Odds ratio = 7.4; IC95% 2.3-11.2). This study show that hyperglycemia is a related factor to the increase of serum CRP levels in noncontrolled type II diabetic subjects.