Background: Patients with diabetes need to be knowledgeable enough to confidently engage in the right kind of self-care. Aim: This study aimed to evaluate how a self-care management program affected the knowledge, health behaviors, and self-efficacy of patients with type 2 diabetes. Subjects and methods: A quasi-experimental study design was used. Five health facilities and chronic disease clinics in Port Said governorate, Egypt, were randomly selected to participate in the study. A purposive sample of ninety diabetic patients was collected for the six-month duration of the study. Tools:  The Diabetes Self-Care Activity, the Diabetes Management Self-Efficacy Scale (DMSES), and the Self-Administered Diabetic Knowledge Questionnaire Test (pre/post). Results: Following the implementation of a diabetes self-management education program, the mean diabetes management self-efficacy scores of the diabetes patients increased to 81.59 ± 3.41. Approximately 55.6% of patients with diabetes had good knowledge and 100% of patients had satisfactory self-care practices. Conclusion: Implementing the self-care management program resulted in positive outcomes for diabetic patients regarding their knowledge, health behaviors, and self-efficacy. All diabetic patients demonstrated satisfactory self-care practices, and there was a significant increase in mean self-efficacy scores following the program. Recommendation: All diabetic patients attending health care centers should be presented with trustworthy evidence-based information, awareness campaigns, and the production of illustrated posters and booklets on type 2 diabetes self-care management, as well as important points for accurate assessment of self-efficacy level.