The purpose of the current study was to examine executive function (EF) in adolescents with type 1 diabetes using both performance-based and questionnaire measures in relation to diabetes indicators. Adolescents age 13–17 completed performance-based measures of EF and measures of adherence. Adolescents’ parents reported on adolescents’ EF and adherence. HbA1c and frequency of blood glucose monitoring (glucometer data) were obtained from adolescents’ medical records. None of the performance-based measures of EF were significantly associated with adherence or with HbA1c. Parent-reported problems with EF were associated with poorer adherence, and adolescents who scored in the impaired range of the Behavioral Regulation Index of EF had significantly poorer adherence (both parent-reported adherence and frequency of blood glucose monitoring) and higher HbA1c than those in the normal range. Our findings suggest that parent-reported measures of EF may be more strongly linked to diabetes indicators than performance-based measures.