The state of the immunophenotype of blood lymphocytes in patients with newly diagnosed type 2 diabetes in the post-COVID period

Background. Today, the indicators of the subpopulation blood composition are one of the key characteristics of immune function. These parameters are of particular importance in patients with newly diagnosed type 2 diabetes mellitus (T2DM) in the post-COVID period. However, research data on the state of the lymphocyte immunophenotype in patients with newly diagnosed T2DM with different body mass index (BMI) in the post-COVID period are extremely scarce and controversial. Aim of the study: to determine the lymphocyte immunophenotype (CD3+, CD4+, CD8+, CD20+ and CD56+ T cells) in the blood of patients with newly diagnosed T2DM with different BMI in the post-COVID period. Materials and methods. The study involved 98 individuals with the onset of T2DM that occurred within 3 months after COVID-19, with different BMI, and 94 patients with the onset of T2DM in the pre-pandemic period and with different BMI. The comparison groups consisted of 93 normoglycemic people who have suffered coronavirus disease, with different BMI, and 88 normoglycemic people with different BMI without COVID history. The examined subjects were divided into 4 subgroups depending on BMI: 1) < 25.5 kg/m2; 2) 25.9–29.9 kg/m2; 3) 30.0–34.9 kg/m2; 4) > 35.0 kg/m2. The lymphocyte immunophenotype in the blood was determined by flow cytometry using a FACStar plus laser cytofluorimeter and a panel of monoclonal antibodies to lymphocyte membrane antigens. Results. Patients with TD2M in the post-COVID period were characterized by a significant decrease in the absolute number of all lymphocyte subpopulations compared to pre-COVID patients and normoglycemic people before and after COVID. When distributing patients into 4 subgroups according to BMI, a progressive decrease in CD3+, CD4+, CD8+, CD20+ and CD56+ T cells was revealed compared to those with newly diagnosed T2D before COVID-19, in whom, on the contrary, a progressive increase in all lymphocyte subpopulations was noted. A similar increase in the absolute number of CD4+ T cells depending on BMI was also noted in normoglycemic individuals, but it was less pronounced. Conclusions. Patients with newly diagnosed T2DM in the post-COVID period were characterized by a decrease in the number of all lymphocyte subpopulations in the peripheral blood, which is most pronounced in concomitant obesity. It indicates the immunosuppressive effect of coronavirus disease on the state of the immune system in patients with the onset of T2DM in post-COVID period and with different BMI.