Background: Diabetes Mellitus (DM) is a chronic disease with a continuously increasing incidence that requires long-term management. Glycemic control largely depends on patients’ ability to perform self-care. Dorothea Orem’s Self-Care Deficit Nursing Theory emphasizes that individuals require support when they experience limitations in meeting their self-care needs. In primary care settings, family involvement is an important factor in the effective management of DM; however, evidence mapping regarding the family-based implementation of this theory remains limited. Objective: This scoping review aimed to map the scientific evidence regarding the implementation of a family-based Self-Care Deficit Nursing Theory approach for glycemic control among patients with DM in primary care settings. Methods: A scoping review was conducted following the PRISMA-ScR guidelines. Literature searches were performed in Google Scholar, PubMed, and ScienceDirect for studies published between 2015 and 2025. Eligible studies included primary quantitative, quasi-experimental, randomized controlled trial (RCT), and mixed-methods studies addressing self-care, family support, and glycemic control among patients with DM in primary care settings. Results: Most studies demonstrated that family-based interventions contributed to improvements in dietary adherence, physical activity, self-monitoring of blood glucose, and treatment adherence. These approaches also enhanced patients’ motivation and consistency in performing self-care activities, thereby supporting better glycemic stability. Conclusion: Family-based self-care approaches have the potential to improve glycemic control among patients with Diabetes Mellitus in primary care settings. Integrating nursing theories into family-centered interventions may strengthen the delivery of community-based nursing care.