Few studies have identified determinants of glycemic control (HbA1c) and diabetes-specific quality of life (DSQoL) in adults with type 1 diabetes. To identify factors predicting outcomes following structured diabetes education. 262 participants completed biomedical and questionnaire assessments before, and throughout 1 year of follow-up. The proportion of variance explained ranged from 28 to 62 % (DSQoLS) and 14–20 % (HbA1c). When change in psychosocial variables were examined, reduced hypoglycemia fear, lower ‘perceived diabetes seriousness’, greater self-efficacy and well-being predicted QoL improvements from baseline to 3-months. Increased frequency of blood glucose testing predicted improvements in HbA1c from baseline to 6-months. Greater benefits may be achieved if programs focus explicitly on psychosocial factors. Self-care behaviours did not predict HbA1c suggesting existing assessment tools need refinement. Evaluation of treatment mechanisms in selfmanagement programs is recommended.