Background: Self-management of type 1 diabetes mellitus (T1DM) can be challenging for people with intellectual disability. Often, parents provide health support due to lack of appropriate services outside the home. The study aim was to identify barriers and facilitators to T1DM self-management for young adults with intellectual disability and the implications for health promotion. Methods: Five male participants with intellectual disability, aged 17-26 years, and seven parents were interviewed between October 2017 and February 2019. Interview data were descriptively analysed. Findings: Two categories for barriers and facilitators were identified: 1) Diabetes self-management is complex (carbohydrate counting, blood glucose level monitoring, insulin therapy); 2) support for diabetes care (reliance on parents and carers, the National Disability Insurance Scheme, mainstream diabetes service support). Conclusions: Parents are critical for the support of people with intellectual disability and T1DM in the absence of disability staff with appropriate health skills.