People with coexisting type 1 and 2 diabetes and mental illness have a higher mortality rate compared to the general population, among other reasons due to unregulated diabetes. One explanation might be the complexity of managing both conditions. In this interview study, we explored the accounts of delivered diabetes and mental health care of 16 individuals living with coexisting diabetes and mental illness in Denmark. A thematic analysis by Braun and Clarke was applied in the analysis. Some of the participants described the care for diabetes and mental illness to be inextricably linked to each other. Therefore, health care providers ought to focus and knowledge of both conditions as essential components in the care provided. The participants accounted for support needs in other settings beyond diabetes and mental health outpatient clinics, such as the family doctor, residential institutions, and community care. However, the inefficient collaboration between these health care settings is one of the barriers to supporting the participants' self-management.