The development of type 1 diabetes mellitus is preceded by the appearance of autoantibodies in the blood for several years. Their detection is an early sign of an autoimmune process directed against beta cells of the pancreas. Such antibodies include antibodies to glutamate decarboxylase (GAD), tyrosine phosphatase (IA-2), insulin (IAA), zinc transporter ZnT8, and cytoplasmic components of islet cells (ICA). Tyrosine phosphatase (IA-2) is an islet cell autoantigen located in the granules of pancreatic beta cells. Antibodies to IA-2 are detected in 50-75% of patients with type 1 diabetes mellitus, often even before the first clinical symptoms appear. In children, these antibodies are more common than in adults, and may indicate a more aggressive destruction of beta cells. As the disease progresses, the level of autoantibodies gradually decreases, which is associated with the destruction of cells to which the immune response is directed. Therefore, with a prolonged course of type 1 diabetes, their diagnostic value may decrease. The determination of antibodies to GAD, IA-2, insulin and ICA is especially important when examining the next of kin of patients with type 1 diabetes. The very fact of detecting autoantibodies already indicates an increased risk of the disease. In the presence of several types of antibodies, the probability of developing diabetes is significantly higher than with an isolated increase in one indicator. It should be borne in mind that antibodies to IA-2 are more often found in children with classical type 1 diabetes and much less often in latent adult autoimmune diabetes (LADA). The sensitivity of the IA-2 test for the diagnosis of type 1 diabetes mellitus is about 57%, and the specificity is 99%. In children with elevated levels of tyrosine phosphatase antibodies, the risk of developing insulin-dependent diabetes reaches approximately 65% within 5 years. Early detection of autoantibodies makes it possible to determine a predisposition to the disease, start monitoring in a timely manner and take preventive measures to reduce the risk of complications.