ABSTRACT Black men are more likely to be diagnosed with Type 2 diabetes (T2D) compared to non-Hispanic White men. Black men with T2D also experience suboptimal glycemic control compared to non-Hispanic White men, resulting in a higher risk for complications associated with T2D. A growing body of literature demonstrates the critical role of gender in the management of health behaviors for chronic conditions such as T2D; male gender norms can negatively impact implementing healthy behaviors. Broader literature demonstrates that gender-based beliefs, like maintaining a strong image to the outside world, impede engaging in healthy behaviors. These studies suggest that tailoring T2D self-management interventions to address the needs of Black men may be critical to helping them to achieve optimal health outcomes. Peer leaders are trained lay individuals who provide ongoing T2D self-management support to people with T2D, particularly in minority communities. Despite studies showing that T2D management interventions using peer leaders have been successful, the majority of peer leaders and participants in those studies are women. The limited studies to date suggest that Black men with T2D prefer peer-led, male-to-male T2D programs; however, this research consists primarily of nonrandomized, small sample feasibility studies focused on disease prevention and screening. The proposed study will develop and preliminarily validate the effectiveness of an adapted Peer Leader Diabetes Self-Management Support (PLDSMS) intervention designed to improve diabetes-related self-management behaviors in Black men with T2D. The proposed study includes a developmental phase (development of the intervention with expert feedback, followed by feasibility testing with Black men) and a pilot validation phase. This study aims to 1) tailor existing PLDSMS interventions by consulting Black male peers with T2D in 2 focus groups and modifying the peer leader training content to focus on material appropriate for men using Self- Determination theory, Autonomy Support and the Empowerment Approach as guiding frameworks, and 2) to conduct a pilot validation phase [pilot randomized clinical trial (RCT)] to evaluate participant recruitment and retention rates, treatment and intervention satisfaction, and estimate intervention effect sizes on our primary outcomes (self-management behaviors and glycemic control [HbA1c]) as well as on secondary outcomes in a 36-week RCT with a repeated measures design. Participants (n=60) will be randomized into the adapted PLDSMS intervention group or Enhanced Usual Care group. If successful, this study will lead to the development of an R01 intervention that will address the unique needs of Black men with T2D, helping them to achieve optimal T2D self-management and health outcomes.