Introduction: The COVID-19 pandemic has marked the arrival of many economic, psychological, social, medical and other impacts around the world. One of them is the accelerated aging of the population. Scientific evidence from literature suggests that glucose levels increase with age, and hyperglycemia contributes to the development of accelerated aging. The purpose of the study: to determine the concentration of glycated hemoglobin in the blood in patients of middle, elderly and senile age during the pre-COVID and post-COVID periods. Materials and methods: 254 results of analysis of glycated hemoglobin concentration in patients' blood were studied. In the sample, the results of the analyses are distributed by study periods: pre-COVID period (01.09.2019 - 31.12.2019) and post-COVID period (01.09.2022 - 31.05.2023). In each of the study periods, the results of analysis of the analyte level of only certain age periods were included: middle-age (45-59 years), elderly age (60-74 years), senile age (75-89 years). Results: Median glycated hemoglobin concentration among middle-aged subjects increased from 5.50% to 5.80% (p = 0.001) in the post-COVID period, and among the elderly, the indicator remained the same - 5.6%, but in the post-COVID period, quartile values significantly increased - 25% (5.35 to 5.50%) and 75% (5.70 to 6.00%), therefore, the differences in samples were statistically significant. There were no significant differences in glycated hemoglobin values in the senile age category (p = 0.160). Discussion: The data obtained on the assessment of the dynamics of glycated hemoglobin concentration in blood in patients in the post-COVID period were comparable to the literature, there was an unfavorable increase in glycated hemoglobin levels in the post-COVID period in middle-aged and elderly compared to the pre-COVID period. Ambiguous conclusions can be associated with a number of factors. Conclusion: Thus, the study showed an unfavorable increase in the concentration of glycated hemoglobin in the blood in the post-COVID period in middle-aged and elderly people. The results obtained are comparable to the scientific literature. However, it should be noted that there are certain contradictions in the literary data. Ambiguous conclusions can be associated with a number of factors, which necessitates further research in this direction.