OBJECTIVE: Arterial blood pressure was followed in 868 patients with type 1 diabetes aged 6.0-19.9 years in 95 centers in Germany and Austria. RESEARCH DESIGN AND METHODS: European blood pressure reference data for 28,043 children and adolescents were used with respect to age and sex. Data were stratified into three groups: prepubertal, pubertal, and postpubertal. RESULTS: Up to 4% of the participants in the younger age-groups and 13.9% of the postpubertal patients exhibited blood pressure values >97th centile. Blood pressure levels correlated with A1C level and BMI Z score. Tracking of blood pressure revealed that children with elevated blood pressure had higher blood pressure in adolescence and young adulthood. CONCLUSIONS: Patients with higher blood pressure in childhood showed elevated blood pressure later in life. We need to focus on the diagnosis of hypertension in children with type 1 diabetes and to study the efficacy of early intervention.