Background: Diabetes mellitus is a chronic condition that can be correlated with lifestyle adjustments and medical treatment. Insulin treatment is one component of a comprehensive diabetes treatment plan that is necessary for all persons with type I diabetes. Saudi Arabia is a high prevalence country (12-23.7%) with about 319509 cases of diabetes mellitus (NIDDM and IDDM). Hence the aim of this study is to investigate the performance of diabetes patient regarding insulin injection technique. Material & Methods: The study was conducted in two diabetic clinics. The study sample included all patients managed at the study setting (45 patients) who had records and code number for follow-up and were undergoing insulin therapy for at least 1 year. The study followed a cross-sectional approach. Two tools were used in this study: Tool I: Specially designed self-administered questionnaires for diabetic patients that was divided into two sections, dealing with patients' knowledge. Tool II: An observation checklist to monitor the injection technique followed by the patient. Results: It was revealed that there were statistical significant differences in patients' perfarnance between before and after the health education instruction regarding subcutaneous insulin injection. Conclusion & Recommendations: Diabetes education is the cornerstone of the care of diabetes patients who aspire to achieve successful health-related outcomes. In this respect, the role of the nurse as the “coordinator" is essential to ensure that the quality of diabetes education is delivered through a coordinated systematic approach. Optimal injection technique is essential for good glycemic control. A great deal of time and effort are often sent educating patients when insulin therapy is initiated. Recommendation and advice given by nurses or health care professionals need to be revised and updated as professional understanding of insulin deposition and absorption improves.