ROBO4 and Hyperglycemia: Hyperglycaemia is the initial cause of DR, resulting in pathological changes in the microvasculature and inducing hypoxia in the retina; hyperglycaemia and hypoxia may then interact and contribute to the progression of DR.7 Accordingly, changes in HIF‐1α, SP1 and ROBO4 in ARPE‐19 cells under hypoxia were similar to those under high‐glucose conditions.