The International Society for Pediatric and Adolescent Diabetes has identified school as a critical context for adolescents with type 1 diabetes (T1D) who typically hold a fluctuating, though growing, amount of responsibility for diabetes self-management across this time. When parents use frequent autonomy-supportive communication to maintain a mutually agreeable sharing of responsibility for diabetes management with their adolescent, better outcomes are achieved. There is, however, a dearth of research examining the way adolescent responsibility is managed at school. This cross-sectional study investigated adolescents’ perspectives of sharing responsibility for T1D management at school and the extent to which these were concordant with parent perceptions. Sixty adolescents (10–19 years) and fifty-five parents completed questionnaires measuring the perceived impact of diabetes on adolescents’ school activities and respective involvement in the management of responsibility for school-based diabetes care. Adolescent questionnaires also measured perceptions of autonomy supportiveness (Health Care Climate Questionnaire) and communication quality (frequency, mode, autonomy), in relation to diabetes management. Differences by age and inter-rater agreement between parent and adolescent dyads were examined. Results showed that parents and adolescents did not agree about their relative involvement in setting up diabetes management strategies or the impact of diabetes on school activities. There was no difference in the involvement of older adolescents relative to younger students. Adolescents predominantly communicated about school diabetes care in person, though some reported no communication with school staff (25%) or healthcare workers (36%). Only thirty nine (65%) reported having a diabetes school plan. Nineteen (32%) perceived little or no involvement in setting up diabetes care strategies for the year and most had not attended a school-related meeting. These results suggest more explicit inclusion of adolescents in formal school support strategies may better represent their unique perceptions of responsibility, enabling the consensual sharing of responsibility that is associated with better outcomes.