ObjectiveYoung adulthood is a time of significant challenges and risks for people with type 1 diabetes. Poor outpatient clinic attendance is common among young adults with type 1 diabetes. The aim of this qualitative study was to develop a theory explaining attendance at a hospital-based diabetes clinic.DesignUsing a grounded theory methodology, data were collected through semi-structured qualitative interviews.MethodTwenty-nine people (21 young adults with type 1 diabetes and eight service providers) from one hospital-based diabetes clinic were interviewed. Interviews wereaudio-recorded, transcribed, and analysed according to grounded theory methodology.ResultsRelationships between young adults and service providers is the core category of this theory. Collaborative relationships between young adults and service providers increased the perceived value of attendance and reduced the vulnerability of young adults to the barriers within the existing service, such as meeting unfamiliar service providers. Relationships between young adults and service providers weredeveloped following opportunities for contact (e.g., structured education programme or crisis of diabetes), and facilitated engagement with the service and further attendance. Barriers to clinic attendance included young adults' negative perceptions of their diabetes self-management and a lack of value associated with attending.ConclusionThe diabetes clinic was described as an important and valued resource by young adults and service providers. Collaborative relationships between young adults and service providers enhanced service provision in this study. According to the results of this study, clinic attendance may be improved by increasing opportunities for relationship development between service providers and young adults.