Interestingly, previous studies demonstrated that DNMT activity and DNMT1 gene expression were significantly increased in both in vitro model and retinal microvasculature from human donors with diabetic retinopathy,16,32,33 and DNMT1 overexpression was also described in DR proliferative stages34 and DNA methylation differences were related to many gene expression changes, especially oxidative stress and inflammation associated genes.16 Data have reported that long-term oxidative stress increases DNMT activity and DNMT1 gene expression35 even in the presence of adequate metabolic control. Here, DNMT1 is linked to diabetic retinopathy.