Irisin levels in patients with type 2 diabetes mellitus depending on body composition and vitamin D status

Background. Obesity is one of the leading pathogenetic links in the development of type 2 diabetes mellitus (T2DM) and is accompanied by impaired energy homeostasis, formation of insulin resistance and activation of chronic low-grade inflammation. These processes lead to the progression of metabolic disorders and increase the risk of cardiovascular complications. An important role in the regulation of metabolic processes is played by the irisin myokine, which has an anti-inflammatory, cytoprotective and stabilizing effect on glucose homeostasis and lipid metabolism. At the same time, the results of modern studies on changes in its circulating levels in obesity and T2DM remain controversial and depend on clinical and metho­dological approaches. The probable pathophysiological relationship between irisin levels, vitamin D status, skeletal muscle condition, and the nature of metabolic disorders makes further comprehensive studies on their role in the formation of obesity and the development of T2DM relevant. The purpose of the study was to determine the level of irisin in individuals with and without T2DM with different body weights, as well as to investigate the relationships between irisin, body composition, sarcopenia indicators, and vitamin D levels. Materials and methods. One hundred individuals were examined. Serum concentrations of irisin and 25(OH)D were determined by enzyme-linked immunosorbent assay. Body composition was assessed using bioimpedance analysis. Results are presented as mean ± standard deviation. Methods of variation and descriptive statistics were used. Student’s t-test was applied to assess the significance of differences between mean values. Correlation analysis was performed using Pearson’s coefficient, as well as multivariate regression analysis. Results. In obese patients, elevated irisin levels were associated with no high risk of sarcopenia, suggesting preserved or compensatory activation of muscular-endocrine function. In contrast, in patients with T2DM, decreased irisin levels, vitamin D deficiency, and adverse changes in body composition were associated with high risk of sarcopenia and impaired metabolic adaptation. Conclusions. Irisin can be considered a promising biomarker of meta­bolic status, predicting the course of the disease, and individuali­zing the management of patients with metabolic disorders.