Changes of plasma endothelin-1 and vascular endothelial growth factor in diabetic retinopathy and the clinical application value thereof

Abstract

To investigate the levels of plasma endothelin (ET)-1 and vascular endothelial growth factor (VEGT) in type 2 diabetes mellitus patients, evaluate their clinical application values in different clinical types of diabetic retinopathy (DR), and to investigate the correlation between the levels of plasma ET-1, serum VEGF and the types of DR. Peripheral blood samples were collected from 240 patients with type 2 diabetes mellitus, 96 with retinopathy and 144 without retinopathy as controls, diagnosed by ophthalmoscopy and fundus fluorescein angiography. The level of plasma ET-1 was detected with radioimmunoassay, and the serum VEGF was measured by ELISA. Pearson correlation analysis and receiver operating characteristic (ROC) curve analysis were conducted. The expression plasma ET-1 levels of the DM patients with mild non-proliferative retinopathy (NPDR), moderate and severe NPDR and proliferative diabetic retinopathy (PDR), were (178+/-24), (197+/-51), and (231+/-77) ng/L respectively (F=12.186, P<0.01).; and all significantly higher than that of those without DR [(155+/-26) ng/L, all P<0.01]. There was no difference in the expression of VEGF in different courses of DR [(31+/-10), (31+/-8), and (32+/-10) ng/L respectively, F=1.329, P>0.05]. The plasma ET-1 was positively correlated with the type of DR (r=0.504, P<0.01) and the courses of DR (r=0.291, P<0.01). There was a negative correlation between the VEGF level and the type of DR (r=-0.252, P>0.01). ROC curve analysis showed that the plasma ET-1 curve lied in the top left corner, and the curve of VEGF lied under the chance diagonal in all the three different types of DR. The under-curve area of plasma ET-1 were 0.742 at the level of mild retinopathy, 0.723 at the level of moderate and severe NPDR, and 0.857 at the level of PDR. The under-curve areas of VEGF were 0.296, 0.297, and 0.293 respectively. The cut-off points in different types of DR were 173, 197, and 180 ng/L respectively. Plasma ET-1 is superior to VEGF in diagnosing different types of DR. The expression of VEGF in the blood may not accord with that in the retina. The pathogenetic condition of DR in type 2 diabetes mellitus is aggravated with the course of DR.