Assessment of vasomotor endothelial function in patients with diabetes mellitus type 1 at different stages of diabetic nephropathy

Aim. To study a vasomotor endothelial function in patients with diabetes mellitus (DM) type I at different stages of diabetic nephropathy (DN). Material and methods. Twenty six patients with DM type I (I I males and 15 females, mean age 25.9 +/- 4.3 years, mean history of DM 12.9 +/- 3.4 years) entered the study. They were divided into 4 groups: group I -without renal affection, group 2 - with microalbuminuria (MAU), group 3 - with proteinuria (PU), group 4 - with chronic renal failure (CRF). The control group consisted of 7 healthy volunteers. Endothelium-dependent vasodilation (EDVD) was studied in the test with reactive hyperemia provoked by 4-5 min occlusion of the brachial artery by pneumocollar and subsequent assessment of arterial diameter changes after decompression using high-resolution ultrasound dopplerography. Results. Reactive hyperemia resulted in dilation of the artery in all the examinees. This dilation was maximal on second 30 after removal of the collar in the controls, group 2, 3 and 4 and reached 9.2 +/- 2.9, 9.63 +/- 3.62, 725 +/- 5.23 and 4.42 +/- 4.05%, respectively. Resting bloodflow velocity was similar in all the groups and-rose maximally by 95-150%. To estimate EDVD of the brachial artery more precisely, the coefficient of endothelial sensitivity to shift tension was calculated. It made up 0.084 +/- 0.04 (control group), 0.0825 +/- 0.08 (group 1), 0.138 +/- 0.07 (group 2), 0.067 +/- 0.05 (group 3) and 0.052 +/- 0.04 (group 4). Conclusion. At the earliest stage of DN (stage MAU), EDVD is not affected as maximal vasodilation of the brachial artery and endothelial sensitivity to shift tension do not differ from the control values. This means that the stage of MA U is reversible in early treatment, but PU and CRF are not reversible stages associated with depletion of endothelial cells and loss of sensitivity to changing hemodynamic conditions.