The aim of the study was to explore the role of autonomy in participants’ self-management of exercise behaviours and the transfer of responsibility throughout adolescence. The design of this study used qualitative description with information collected and presented using a case study approach. Participants were five emerging adults (aged 18–24) with Type 1 diabetes for a minimum of one year who lived in Canterbury. Data was gathered through three sources: a semi-structured interview seeking self-reported exercise throughout adolescence, a set of questionnaires based on four instruments, and physical activity performed over a week as recorded by an activity monitor. All participants achieved autonomy for exercise, however participants achieved autonomy at different ages. Participants’ diabetes self-management and physical activity levels varied according to their stage of life and lifestyle. They received varying advice about exercise from health professionals. Participants sought to determine their own exercise choices during adolescence, leading them to obtain a driver licence to be independent of parental transport. Three of the five met current guidelines for physical activity levels, and another met recommendations by her clinician. Policy implications regarding healthcare advice and barriers to exercise for young people are discussed, as are limitations of the research and future avenues for research.