It was found that in patients with type 2 diabetes mellitus, vasopathy, which forms the risk of thrombosis, is very common. The widespread prevalence in developed countries of type 2 diabetes supports the high interest of many researchers. Much attention in this pathology is given to vascular control over the aggregation of blood cells. The aim of the study was to study the state of disaggregation properties of blood vessels in relation to erythrocytes in patients with type 2 diabetes mellitus. 36 patients with diabetes mellitus of type 2 of the second adult age were examined. The control consisted of 26 healthy persons of the second adult age. The study uses biochemical, hematological and statistical methods. In patients, an increase in the cholesterol content in erythrocyte membranes, a decrease in the level of phospholipids in them, and activation of lipid peroxidation were found. In addition, they showed excessive activity of spontaneous aggregation of erythrocytes. It was accompanied in these patients by the weakening of vascular disaggregation control over them. The changes found in the examined category of patients should be considered as a consequence of metabolic disorders, expressed vasospasm and activation of lipid peroxidation.