Background: Functioning in a peer group plays an important role in child development. Building self-esteem of children depends on many factors such as physical health, self-evaluation of their physical performance, academic achievement, social support, family relationships, as well as relationships with peers and teachers. Importance of contacts with peers increases during school-age. At this time children are not able to reject the opinion of other people and subject their behaviour completely to the expectations of their peers. When the need for emotional contact is not satisfied, the complex of being different appears. Isolation within group causes a sense of inferiority, the child becomes passive and resigned. Children, who are chronically ill, rejected or isolated often follow negative emotions in their actions, they become aggressive towards other children or do not want to continue learning. Often the decision about an individual teaching plan results in further isolation of the child. The child’s position in the peer group affects the developing personality, self-confidence and self-esteem. Aim of the study: The aim of the study was to determine the interpersonal relationships of young school-aged children with type 1 diabetes in their peer groups. Material and methods: The study was conducted on children with type 1 diabetes and their parents, who are supervised by Clinic of Diabetes, Regional Medical Center in Opole. The research tool used in both groups was a questionnaire consisting of open and closed questions elaborated by the authors of this study. Results: 73% (41) of evaluated children declared that diabetes does not hinder their performance at school. 93% (55) children claimed that they do not hide their condition from their peers. In addition, 61% (34) talk about their illness with their peers and 69% (38) of them can count on their peers’ help in self-control of diabetes. 71.9% (46) of parents of children with type 1 diabetes allow their children to participate in school trips and 68.8% (44) to participate in school competitions. Conclusions: In most children, diabetes does not affect children’s performance at school. They participate in classes, are accepted and liked in their peer group. Chronically ill children should be able to participate in all types of activities as much as their healthy peers. It seems necessary to continue studies on performance of young school-aged children with type 1 diabetes in their peer group.