NOS2 and Hyperglycemia: Hyperglycemia induces the production of reactive oxygen species (ROS) and the expression of many pro-inflammatory factors in the diabetic retina including inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) [20].