Background events leading to the aforementioned consequences of diabetes are proved to involve ischemic-reperfusion injuries to the retina (Calderon et al., 2017) based on or followed by changes of proteins such as heme oxygenase-1 (Varga et al., 2013), sirtuin 1 (SIRT1), or matrix metalloproteinase 9 (MMP9) (Wachal et al., 2020). This evidence concerns the gene MMP9 and diabetes mellitus.