The central role of hyperglycemia in NPDR lies in its activation of various pathways, including the polyol pathway, the accumulation of advanced glycation end products (AGEs), the protein kinase C pathway, the hexosamine pathway, the vascular endothelial growth factor (VEGF) pathway, the nuclear factor kappa-B (NF-κB) pathway, and the Janus Kinase—Signal Transducer and Activator of Transcription JAK-STAT pathway. This evidence concerns the gene VEGFA and non-proliferative diabetic retinopathy.