The objective of the present work was to estimate the degree of rigidity of the vascular wall and endothelial function in the patients with type 1 diabetes mellitus at different stages of diabetic retinopathy and in its absence. The study included 118 patients at the age from 18 to 40 years presenting with type 1 diabetes mellitus more than 5 years in duration. The patients were divided into several groups based on the stage of diabetic retinopathy (DR). The control group was comprised of 23 healthy subjects. The contour pulsed wave analysis and the reactive hyperemia test were performed with the use of an Angioscan device. All the patients gave the informed consent to participate in the study. The aortic stiffness index (SI) in all groups of the patents with DM1 and DR was higher than in the healthy subjects. However, the SI values remained normal in the DM1 patients without DR. An increase of SI values was unrelated to the presence of arterial hypertension. The analysis of RI values revealed no statistically significant differences between the groups. The reactive hyperemia test has demonstrated a decrease in the increment of the post-occlusive signal amplitude in a large number of patients suggesting endothelial dysfunction. This decrease was apparent even in the patients exhibiting no signs of retinal damage. However, despite the overall decrease of this parameter, many patients showed its paradoxically high values that probably reflected the elevated baseline level of nitric oxide. The increase of aortic stiffness index with the progression of diabetic retinopathy may be used as an early marker of macrovascular complications even in the patients without arterial hypertension. The lowering of the increment of the post-occlusive signal amplitude in the patients having no signs of retinal damage is indicative of endothelial dysfunction as early as the preclinical stage of DR development. The paradoxically high increment of the signal amplitude is supposed to be associated with the elevation of the baseline level of nitric oxide that in its turn reflects the severity of inflammation and is a factor of high risk of progression of angiopathies.