This study aims to show the distribution of different RAS gene polymorphisms—ACE I/D gene polymorphism and AGTR1 gene polymorphism—in adolescents with hypertension and T1D in the population of Serbia and analyze the association between ACE and AGTR1 genotypes, blood pressure, and the diurnal variation in blood pressure (dipping status). The gene discussed is ACE; the disease is type 1 diabetes mellitus.