Background: Type 1 Diabetes Mellitus is one of the most difficult non-communicable disorders to treat in children and is a global health issue. Diabetes self-care is particularly challenging for children. Aim: To assess self-care knowledge and practice among preparatory diabetic school students at Aswan City. Design: A descriptive cross sectional research. Study Setting: At preparatory governmental schools, in the Aswan City. Sample: convenience sample of 99 students diagnosed with diabetes from the previous study setting. Tools for data collection: Tool (I): Structured interviewing questionnaire include 2 parts: First part: demographic characteristics of students, demographic characteristics of parents, and diabetic history of students. Second part: Students‟ knowledge about diabetes. Tool (II): Cstsilkheh of self-care practice. Results: More than half of them had good knowledge about diabetes, while less than one third of them had fair knowledge and less than one fifth of them had a total poor of knowledge. This study also highlighted that nearly one fifth of the students had satisfactory self- care practice, while more than two fifths of them had unsatisfactory self-care practice. Conclusion: study confirmed that there was highly statistical considerable difference positive correlation between the overall knowledge and the overall practices. Recommendations: Programs for in-service education on diabetes management and emergency protocols for hypo- or hyperglycemia should be made available to school health nurses.