Background: Diabetes Mellitus is an endocrine disorder, characterized by hyperglycemia that is, high blood sugar levels. Insulin is one of the oldest valuable anti-diabetic medications available and also the most effective agent in dropping hyperglycemia when used in appropriate doses. Better insulin self-administration is associated with good knowledge and a positive attitude of a patient on insulin self-administration. So, the present study aimed to explore the effect of structured educational program on diabetic patients' knowledge attitude, and practices regarding self-administration of insulin injection. Research design: To achieve the goal of this study, one group pretest post-test using a quasi-experimental research design was employed. Setting: The study was conducted in the Diabetic Outpatient Clinic at Sohag University Hospital. Sample: Within six months a convenient sample of one hundred diabetic patients who were on insulin therapy was included in the current study. Tools: Four tools were used: Tool (I) Structured interview questionnaire included two parts as follows Part (1) Patients' demographic data and Part (2) Patients' medical history, Tool (II) (3) Patients' knowledge about self-administration of insulin injection, Tool (III) Patients' attitude regarding self-administration of insulin injection, and Tool (IV) Patients' practice about self-administration of insulin injection. Results: The study indicated that there was a statistically significant improvement in patient's knowledge, attitude, and practices regarding self-administration of insulin injection among diabetic patients post- structured educational program than pre- structured educational program. A statistically significant correlation was observed between patients' knowledge, attitude, and practices post- post-structured educational program. Conclusion: The findings of the study concluded that a structured educational program was effective in enhancing the patients' knowledge and improving their attitude regarding self-administration of insulin injections among diabetic patients. Recommendations: With the right instruction and an insulin injection demonstration, the gaps surrounding the self-administration of insulin injections should be filled. There should be widespread access to comprehensive insulin usage education programs that emphasize empowering insulin use among individuals with diabetes mellitus and related information as crucial components of diabetes mellitus management programs.