Purpose: to evaluate changes in metabolic parameters of patients with type 2 diabetes mellitus (T2DM) who had/did not have post-COVID syndrome to predict the further course of T2DM. Object and research methods. 121 patients with T2DM were included in the prospective study: 60 patients with post-COVID syndrome and 61 who did not experience post-COVID syndrome. The assessment of vitamin D availability was carried out using the «25-hydroxycalciferol» test, which was performed by the CLIA method, a chemiluminescent immunoassay. Determination of liver enzymes, magnesium, uric acid were condacted by colorimetric method. Glycated hemoglobin was determined using the method of high-performance liquid chromatography. The HOMA insulin resistance index was calculated using the formula: HOMA index = glucose (in venous blood) x insulin/22.5. Results. During the analysis, a higher level of body mass index, waist circumference, aspartate aminotransferase, glycated hemoglobin, HOMA index and a lower level of 25-hydroxyvitamin D (25-OH D) (p<0.05) were obtained in comparison with patients without post-COVID syndrome. No significant difference was found between the groups of patients who experienced post-COVID syndrome and those who did not have post-COVID syndrome, according to the following indicators: age, history of T2DM, alanine aminotransferase, uric acid, magnesium. Conclusion. The obtained data indicate the possibility of predicting a more severe course of T2DM in patients with post-COVID syndrome, which requires careful monitoring and compensation of carbohydrate metabolism due to the correction of the scheme of antidiabetic therapy and vitamin D deficiency.