Research thesis encompassing two papers: Psychological factors associated with diabetes self-management among adolescents with Type 1 diabetes: a systematic review The purpose of the review was to determine what psychological factors are associated with diabetes self-management. Twenty-one articles were determined to be eligible for this review. Numerous psychological factors were found to be associated with self management; however, correlations were typically small to moderate. Study validity was variable and there was little overlap between psychological factors examined. Variables are presented in a narrative synthesis. The strongest associations were found between social anxiety and diet (among boys); greater intrinsic motivation, conscientiousness and diet; and extraversion and exercise. Evidence exists for relationships between psychological factors and diabetes self-management but due to the individual nature of the studies, firm conclusions cannot be drawn. Future research needs to attempt replication and utilise validated measures to provide a stronger evidence base from which to develop theory for this population. The relationships between diabetes distress, illness perceptions and glycaemic control in adults with Type 2 diabetes This study aimed to investigate whether illness perceptions moderate the relationship between diabetes distress and glycaemic control. Participants with Type 2 DM attending diabetes outpatient clinics (n = 82) completed the Diabetes Distress Scale 17, Brief Illness Perceptions Questionnaire and the Patient Health Questionnaire 9 as well as providing demographic and clinical information. Most recent HbA 1 c and BMI were collected from medical records. Personal Control was the only significant contributor in the final regression model predicting HbA 1 c. The relationship between regimen-related distress and HbA 1 c was mediated by personal control. Moderating effects were non-significant. Personal control has an important role in explaining the link between diabetes distress and HbA 1 c. Psychological interventions seeking to improve HbA 1 c need to address individuals' perceptions of personal control.