In light of the growing prevalence and healthcare costs of diabetes mellitus, it is critically important for healthcare providers to improve the efficiency and effectiveness of their diabetes care. A key element of effective disease management for diabetes is support for patient self-management. Barriers to care exist for both patients and healthcare systems. As a result, many people with diabetes do not get the care and support needed to successfully manage their diabetes.Disease management approaches that incorporate peer support may be a promising way to help provide self-management support to patients with diabetes. Trained peers provide emotional support, instrumental (tangible or material) support, education, and skills training to those they serve, and outreach and care coordination for provider systems. They play a unique role that complements and supports clinical care.To describe how peers are currently supporting diabetes care, a number of databases were searched for studies describing the roles of peers using relevant key words. This paper reviews current literature that describes the roles and duties of peers in interventions to improve diabetes care, with a focus on their contributions to six essential elements of self-management support: (i) access to regular, high-quality clinical care; (ii) an individualized approach to assessment and treatment; (iii) patient-centered collaborative goal setting; (iv) education and skills training; (v) ongoing follow-up and support; and (vi) linkages to community resources.Peers worked under a variety of titles, which did not define their duties. The scope of their work ranged from assisting health professionals to playing a central role in care. Providing education and follow-up support were the two most common roles. In all but one study, these roles were carried out during face-to-face contact, most frequently in community sites.A growing body of literature supports the value of peer models for diabetes management. Additional research can answer remaining questions related to such issues as cost effectiveness, sustainability, integration of peers into health and social service delivery systems, and recruitment, training, and support of peers. Continuing to develop and evaluate innovative models for more effectively mobilizing and integrating peers into diabetes care has great potential for improving diabetes outcomes worldwide.