The quality of the doctor–patient relationship has been shown to impact upon a number of health outcomes in diabetes, including psychological well-being. This cross-sectional study investigated illness perceptions as mediators of the association between the doctor–patient relationship and diabetes-related distress. Individuals with diabetes completed questionnaires which measured the perceptions of their relationship with their doctor, diabetes-related distress and illness perceptions. The association between doctor–patient relationship and diabetes-related distress was fully mediated by Personal Control, suggesting that the individuals’ beliefs surrounding their capacity to control their diabetes mediate the association between the doctor–patient relationship and diabetes-related distress.