SOD3 and diabetic retinopathy: Acetylated H3K9 is reduced in Glut2 promoters, which is required for maintaining glucose homeostasis, and can be reversed by treatment with exendin-4 (a diabetic inhibitor).In conjunction with this, a study has shown that exendin-4 can treat diabetic retinopathy by inducing SOD3 promoter acetylation of histone H3 to boost its expression in endothelial cells.