Diabetes is considered one of the most progressive metabolic syndrome that affects up to 7% of the people worldwide with many complications. Although the exact molecular mechanisms involved are still controversial, diabetic infertility represents a common complication and, in this regard, recent research offers a promising candidate where mesenchymal stem cells have been applied in dealing diabetes and its complications. The present study investigated the ameliorative effect of breast milk mesenchymal stem cells (Br-MSCs) in diabetic testicular dysfunction rat model with emphasis on testicular immunomodulation and proliferating cells nuclear antigen (PCNA) expression. Forty-five adult male Sprague Dawley rats (8-12 weeks old) were divided into three groups such as control (n=15), diabetic (n=15) and diabetic-treated and, 14 days post induction of type 1 diabetes (n=15), were administered double intraperitoneal injection of Br-MSCs. Testicular gene expression interleukin 1 beta (IL1β), interleukin 6 (IL6), interleukin 8 (IL8), proliferating cell nuclear antigen (PCNA), transforming growth factor beta (TGFβ1) and interleukin 10 (IL10) were determined. Br-MSCs administration elicited a significant improvement in sperm count (P < 0.01), motility (P < 0.01) and abnormality (P < 0.01), a significant reduction (P < 0.001) in pro-inflammatory markers IL1β, IL6, IL8, and TGFβ1, a significant increase (P < 0.001) in anti-inflammatory testicular marker IL10, and the cell proliferation marker PCNA. The study conclude that Br-MSCs could ameliorate diabetic infertility via immunomodulatory effect and create a local anti-inflammatory microenvironment that reduced further testicular dysfunction.