The article examines the features of emerging disorders of the immune system in children suffering from diabetes mellitus, as well as the susceptibility of such children to various diseases. The authors note that children with diabetes have some disorders of the immune system, which, combined with high glycemia, increase the risk of infections and their severity, and they should be immediately detected and treated. Infections, even typical childhood diseases, significantly interfere with glycemic control. As a result of the infectious process, the level of counter-regulating hormones, cortisol, adrenaline and growth hormone increases, which leads to increased neoglycogenesis, glycogenesis and increased insulin resistance. This increase in insulin resistance requires adjustment of the patient's usual insulin dose, both basal and bolus. There are usually several hours or days before such a need arises, and it may take time to increase the dose, which can lead to hyperglycemia during this period. The presence of an infectious condition, in turn, increases blood glucose levels and increases the risk of decompensation, so pediatricians should be warned against the need to strengthen monitoring and insulin therapy. Patients with diabetes are often not fully vaccinated against various diseases. Vaccines are vital for these patients, significantly reducing the risk of infections and exacerbating the development of the underlying ailment.