Objective: Endothelial dysfunction plays an important role in the development of diabetic retinopathy. The aim of this study was to evaluate endothelial dysfunction using different approaches in patients with type 1 diabete mellitus with early stages of diabetic retinopathy. For this purpose, we investigated the serum levels of cellular adhesion molecules, including intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1) and endothelin-1 (ET-1), which have emerged as specific markers of endothelial dysfunction, and measured the flow-mediated dilatation (FMD), a noninvasive technique used to evaluate endothelial dysfunction.
Methods: The study group included 59 patients with type 1 diabetes mellitus (DM) and 30 age-matched healthy control subjects. The diabetic patients were divided into two groups according to the ophthalmoscopic findings: Group 1, composed of type 1 diabetic patients having no signs of diabetic retinopathy (DRP), and Group 2, composed of type 1 diabetic patients having findings of the early stages of nonproliferative diabetic retinopathy (NPDR).
Results: The serum levels of ET-1 (fmol/mL), ICAM-1 (ng/mL) and VCAM-1 (ng/mL) were 8.52±0.699 vs. 478.39±46.22 vs. 728.64±35.081 in the patients without retinopathy, 8.91±1.354 vs. 451.79±48.262 vs. 863.59±62.37 in the diabetic patients with NPDR and 10.73±1.04 vs. 608.15±74.92 vs. 872.95±57.63 in the control group. There were no significant differences in the serum levels of the three molecules between the groups. The FMD values were 6.51±0.46% in the diabetic patients without retinopathy, 6.66±0.29% in the diabetic patients with NPDR and 6.68±0.51% in the control group. No significant differences were found between the groups.
Conclusion: The early stages of diabetic retinopathy cannot be considered in the evaluation of systemic markers of endothelial dysfunction.