The possible reason might be poor glycemic control or persistent hyperglycemia damages retinal vasculature via activation of pro-inflammatory mediators such as tumor necrotic factor (TNF)-2, interleukin-6, interleukin-1b, angiotensin II, endothelin-1, and vascular endothelial growth factor (VEGF) that could alter retinal blood barrier leads to retinal vessel leakage causing macular edema and nerve scaring which result in retinal detachment and sudden vision loss. This evidence concerns the gene AGT and macular retinal edema.