HIF1A and Hyperglycemia: miRNA-20a overexpression significantly reduced the expression of both VEGF and HIF-1α protein levels in a retinal pigment epithelium cell-line (ARPE-19) exposed to hyperglycemia and hypoxia/reoxygenation [45], and elevated levels of miRNA-20a in serum have been correlated with the progression of DR in patients [48].