- OBJECTIVES: Existing peer support literature in diabetes has focussed predominantly on the health impact it has on the beneficiaries rather than the benefactors. In this mixed-methods study, we examined the effect of delivering peer support (vs receiving) on glycated hemoglobin (A1C) and diabetes distress (DD) at 3 and 12 months as part of a larger diabetes self-management support randomized controlled trial. Maintenance or improvement of outcomes was expected. We also assessed peer leaders' experiences with the program. METHODS: We utilized a sequential explanatory mixed-methods research design that included 58 adults with diabetes (i.e. peer leaders) who completed a 30-hour training program. Peer leaders (n=52) were matched with participants (adults with type 2 diabetes) and invited to undergo assessments at baseline, 3 months and 12 months. Primary clinical and psychosocial outcomes included A1C and DD, respectively. Secondary outcomes were cardiovascular risk factors and depressive symptoms. After the intervention, 17 peer leaders participated in semistructured interviews about their experience. RESULTS: Peer leaders had a mean age of 57.5±11 years and a long history of diabetes (13.9±11 years); over half were male (53.8%) and married/partnered (55.8%). At baseline, peer leaders were at target for A1C (7.0±0.9% [53±10 mmol/mol]) and reported a low level of DD (1.67±0.52). Of the 43 (82.7%) peer leaders who completed the 12-month study, A1C and DD remained stable over 12 months. Secondary outcomes also remained within the normal range from the start to the end of the intervention. CONCLUSION: Delivering peer support may help maintain glycemic control and DD over the long term.