Aim: Children diagnosed with Type 1 diabetes mellitus (T1DM) need supervision in diabetes self-care, and the conditions at school, where they spend a significant part of the day, affect the disease management. The aim of this study is to reveal the problems encountered by preschool and primary school children diagnosed with T1DM regarding disease management at school. Materials and Methods: At this descriptive, cross-sectional study, 50 patients diagnosed with T1DM who were between ages 5-10 were included in the study. The questionnaire pertaining to diabetes management at school was developed by their searcher with respect to the literature, and subsequently file doubt by the patient and/or their parents via Google questionnaire. The data obtained were analyzed by descriptive statistical methods. Results: The patients had diabetes for a mean duration of 5.39±2.56 years. Of all cases, 94% were going to public school. Health care rooms were not present in 78% of the schools, 92% did not have nurses/health-care personnel. Of the participants, 86% were consuming a main meal at school, but the majority of them were bringing their meals from home or going home to eat. The most common problem with nutrition was the consumption of foods that were not suitable for the patient’s diet at school. At school, blood glucose levels were not being measured in 6% of the children. During their time at school, the rate of experiencing hypoglycemia was 40% in children, with the hypoglycemia intervention being most commonly conducted by the teacher (55%). In 77.5% of the children who were receiving insulin at school, the administration was being performed by the mother or father. The most commonly experienced problems regarding insulin treatment at school was the lack of a person trained in administering insulin, and a suitable room for application. The patients’ participation rate for physical education was 98%. While most of the teachers and school administration treated the children with a positive attitude, 18% of the children were exposed to the negative attitude of their peers. Conclusion: Preschool or primary school children diagnosed with T1DM have difficulties in nutrition, blood glucose measurement and insulin administration at school. Most schools do not have health care rooms and/or health-care staff. Since there are no people experienced in administering insulin to this population at school, this is usually done by parents.