THE AIM OF THE STUDY: Using the method of spectral-probability analysis, to evaluate the possibility of predicting an unfavorable outcome of acute decompensation of diabetes mellitus in patients hospitalized in the intensive care unit using a mathematical model. In relation to clinical practice, the implementation of the proposed algorithm for mathematical processing of a set of test data provides the physician with an additional significant criterion for assessing the probability of a tendency to develop type 1 diabetes in healthy children being examined whose brothers or sisters suffer from this disease. MATERIALS AND METHODS: A retrospective analysis of 103 medical records of patients hospitalized in the intensive care unit for acute decompensation of diabetes mellitus was conducted. RESULTS: With regard to the set of analyses of patients with acute decompensation of diabetes mellitus, carried out at the time of admission to hospital, a group of mathematical criteria has been defined that makes it possible to identify patients with a high risk of an unfavorable course of the disease.