Pathophysiological features of thyroid dysfunction in patients with type 2 diabetes and chronic kidney disease (a literature review and own observations)

Background. Diabetes mellitus (DM) is a metabolic di­sease that causes disorders of all types of metabolism. Currently, there is an increasing prevalence of not only DM, but also its serious complications. One of the common chronic complications of DM is diabetic kidney disease (DKD). As of today, it is also known about the effect of DM on other endocrine organs, in particular thyroid gland. Thyroid dysfunction in combination with type 2 DM and DKD are interrelated conditions. In the literature review, the causes, theories of development, stages, course, and criteria for making a diagnosis of DKD are highlighted, probable mechanisms for the development of phenotypes are described. The impact of pathophysio­logical mechanisms of metabolic and secretory disorders on thyroid function has been demonstrated. PubMed and Google Scholar databases were used to search for literature data. The purpose of the study is to investigate the frequency and prevalence of phenoty­pic forms of DKD and the thyroid functional state. Materials and methods. We have analyzed the data of 1,874 patients with type 2 DM who were receiving inpatient treatment at the Lviv Regional Clinical Diagnostic Center, branch of the Center for Endocrinolo­gical Population Health, in 2022 and the first three quarters of 2023. Among them, 56 % were women, 44 % were men. The average age of the patients was 56.1 ± 8.2 years. The frequency and prevalence of phenotypic forms of DKD, the thyroid functional state in such patients were studied. Results. The share of patients with confirmed DKD was 26 % (n = 487). According to the results of the studies, DKD develops by a phenotype of non-albuminuric renal dysfunction in 288 patients (59 %), by an albuminuric phenotype — in 192 cases (39.6 %), and as a progressive decrease in kidney function — in 7 patients (1.4 %). Non-albuminuric renal dysfunction phenotype was 1.5 times more frequent than albuminuric one. Thyroid dysfunction was diagnosed in 166 patients with DKD (34 %). The obtained data confirm the greater prevalence of hypothyroidism as compared to hyperthyroidism in patients with DKD. This allows us to suspect that the structural and functional changes in the kidneys in type 2 DM, which lead to a decrease in the filtration capacity of the kidneys, may be independent of albuminuria. Conclusions. The presence of DKD, regardless of the stage of DM and phenotype, has a direct and indirect effect on the regulation and functioning of the thyroid gland. In turn, adequate production of thyroid hormones is necessary for a balanced metabolism, energy homeostasis and renoprotection. The presence of thyroid dysfunction can be a cause of unsatisfactory control of diabetes and lead to the development of complications.