The possible mechanisms by which hypertension affects diabetic retinopathy are hemodynamic (impaired autoregulation and hypoperfusion) and secondly through Vascular Endothelial Growth Factor, as it has been observed that hypertension independent of hyperglycemia up-regulates the Vascular Endothelial Growth Factor expression in retinal endothelial cells and ocular fluids [37]. This evidence concerns the gene VEGFA and diabetic retinopathy.