Type 1 diabetes mellitus is a chronic endocrine disease commonly affecting children and adolescents, characterized not only by disorders of carbohydrate metabolism but also by changes in the hormonal system. The aim of this study was to perform a descriptive analysis of biochemical and hormonal changes in the course of type 1 diabetes mellitus in children and to determine the relationship between the level of glycemic control and the status of sex hormones. The study included 20 boys with type 1 diabetes mellitus in whom fasting blood glucose, glycated hemoglobin (HbA1c), as well as testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels were assessed. The results showed that in patients with satisfactory glycemic control, sex hormone levels remained within age-appropriate reference ranges, whereas in children with poor glycemic control a decrease in hormonal parameters was observed. Non-adherence to insulin therapy and dietary recommendations may increase the risk of hormonal disorders and delayed pubertal development. The findings highlight the importance of optimizing glycemic control and regular monitoring of hormonal status in children with type 1 diabetes mellitus.