Parents of high school seniors with type 1 diabetes mellitus are faced with many concerns and fears as their adolescent prepares to assume primary disease management responsibility and leave the parental residence. The purpose of this study was to explore the relationship between parental separation anxiety and adolescent self-management and glycemic control. A second aim was to assess the relationship between adolescent self-management and glycemic control. Twenty-three families who had adolescents 16 to 18 years of age in or entering in their senior year of high school were recruited. Adolescents from higher income families reported better self-management skills than those from poorer families (r = 0.410, p = 0.05). Length of time since diabetes diagnosis was inversely related to glycemic control (r = 0.448, p = 0.02), indicating that adolescents who had the disease longer had poorer control. Parental separation anxiety was not related to adolescent self-management. Adolescent self-management was negatively related to glycemic control (r = −0.370, p = 0.08), suggesting that adolescents who demonstrated better self-management skills had improved glycemic control in comparison to adolescents who did not demonstrate effective self-management skills. Paternal, not maternal, separation anxiety demonstrated a significant relationship with glycemic control (r = 0.639, p < 0.001).