**1. Introduction**

Glycans, as potential biomarkers of health and illness, deserve attention in clinical glycomics for early-stage disease diagnosis [1, 2]. It is not surprisingly that abnormal (aberrant) glycosylation of proteins and lipids have been observed in many diseases, including cancer, cardiovascular disease, immune deficiencies and diabetes [3].

Diabetes mellitus (DM) is one of the most common endocrine diseases that have been identified as one of the priority issues for national health systems around the world. Type 1 DM is characterized by a progressive autoimmune destruction

of pancreatic β-cells, leading to insulin deficiency and chronic hyperglycemia [4]. The social significance of this problem is that DM associated with development of numerous concomitant diseases, early disability, and metabolic complications [5]. Insufficient control of glucose level in blood may increased the risk of microvascular (nephropathy, retinopathy, neuropathy) and macrovascular (peripheral artery disease, coronary artery diseases, congestive heart failure, myocardial infarction, stroke) complications. In addition, individuals with DM have increased risk of physical and cognitive disability, depression and cancer [6]. The various complications related to diabetes are determined by changes of blood components. Blood cells (leukocytes, erythrocytes and thrombocytes) are of particular interest because they are directly exposed to high glucose concentrations [7]. Blood cells aggregate strongly to the vessel wall and adhere to each other, which leads to the development of pathological changes in capillary blood flow and microcirculation disorders in diabetes [4–6].

Leukocytes are the major cells of the inflammatory and immune response that defends against different type of infection, consequently these cells are important object for investigation [5]. The сlinical and experimental studies of human blood in case of DM and animals with streptozotocin-induced diabetes demonstrate significant violations of the morphofunctional state of leukocytes. The dysfunction of chemotaxis capacity, adhesion and migration, reduction of phagocytic activity and bactericidal ability of leukocytes correlate with the level of hyperglycemia in blood [8, 9].

The impairment in the functions of immunocompetent cells leads to a decrease in immune defense and the development of chronic infectious/inflammatory processes in organism of people with type 1 diabetes [10]. Chronic inflammation is the main cause of progression of diabetic complications which leads to dysfunction of the extremities, retina, kidneys, nerves, heart and blood vessels. According to statistics, most of patients die from angiopathic complications of diabetes. Screening of complications provides with possibility to reduce the risk for their development and progression [11]. Therefore, expansion of diagnostic methods for characterization of changes in the morphofunctional state of leukocytes and the search for preventive remedies that would ameliorate the clinical condition of patients is a relevant problem today.
