Acute phase proteins have been suggested to be increased in patients with type 1 diabetes. The aim of this study was to evaluate the relationship between serum C-reactive protein (CRP) and intima-media thickness (IMT) and functions of the common carotid artery (CCA) in children and adolescents with type 1 diabetes. Serum CRP levels were measured in 65 children and adolescents with diabetes (33 girls and 32 boys; mean age, 12.7 +/- 3.8 years; range, 7-18; duration of diabetes, 6.9 +/- 3.6 years). Age and diabetes duration, as well as major cardiovascular risk factors including anthropometric and metabolic parameters, were matched between girls and boys. The relations of serum CRP levels to CCA structure and functions were measured by ultrasonography as IMT, cross-sectional compliance, cross-sectional distensibility, diastolic wall stress (DWS), and incremental elastic modulus (IEM). There was no significant difference for serum CRP levels between girls and boys (3.7 +/- 1.3 vs 3.2 +/- 0.4 mg/L; p > 0.05). CRP was positively correlated with IMT (r = 0.49, p = 0.001), IEM (r = 0.24, p = 0.05), DWS (r = 0.58, p < 0.001), and body mass index (BMI) (r = 0.28, p = 0.05). In a multivariate regression model, we included CRP and metabolic and anthropometric parameters such as duration of diabetes, HbA1c, BMI, waist:hip ratio, age, and systolic and diastolic blood pressure as independent variables in the model for CCA structure and functions. CRP emerged as an independent correlation for mean IMT (beta = 0.51, p < 0.001) and DWS (beta = 0.61, p < 0.001). According to our findings, CRP was associated with CCA structure and functions in children and adolescents with type 1 diabetes.