VCAM1 and non-proliferative diabetic retinopathy: The elevations in AGEP, VCAM-1, and VEGF observed in the current study in NPDR and PDR groups in association with the reduction in CTRP3 lead to a more understanding of the mechanism of progression of NPDR and PDR among T2DM patients despite the significant association of HIF-1α rs11549465 with NPDR development as well as the insignificant association of HIF-1α rs11549465 and VEGF rs3025039 with both PDR and NPDR.