Assessment of endothelial function and arterial rigidity in patients with type 1 diabetes at different stages of diabetic nephropathy

Aim. Assessment of vascular stiffness and endothelial function in patients with type 1 diabetes at different stages of diabetic nephropathy and without it. Materials and methods. We examined 93 patients with DM1 aged 18 to 40 years, and disease duration of more than 5 years. The criterion for forming groups is the stage of diabetic nephropathy. Control group consisted of 23 healthy people. The study included an evaluation of the contour of pulse wave analysis, and conducting tests with reactive hyperemia on the unit Angioskan (LTD Angioskan, Russia). Prior to the study of each patients written informed consent. Results. In conducting the analysis of the pulse wave contour index of aortic stiffness was significantly higher in all groups of patients with diabetic nephropathy (DN) compared with healthy subjects. However, when comparing patients with T1D without DN and the control group, significant differences of stiffness index (SI) was not been determined. It should be noted that the increase in value of SI is almost independent of the presence of hypertension in the patient groups. In the analysis of reflection index (RI) values of statistically significant relationships were found. In analyzing the test data with reactive hyperemia we showed a reduction in growth of the signal amplitude in a significant number of patients, which is a sign of endothelial dysfunction, and occurs even in patients without clinical and laboratory signs of kidney damage. However, along with a decrease of this index, a large number of patients have paradoxically high its value, which may indicate a high level of basal nitric oxide. Conclusion. Increase in the stiffness of the aorta, the progression of DN may be an early marker of macrovascular lesions even in patients without hypertension. Reduced growth of the amplitude of the signal after occlusion in patients with no signs of kidney disease, indicates the presence of endothelial dysfunction even in the preclinical stage of diabetic nephropathy. Paradoxically high increase of the amplitude of the signal can indicate the presence of abnormally high basal level of nitric oxide, which is a marker of inflammation, high-risk factor of progression of angiopathies and fibrosis.