Percent methylation of β1-AR (A), β2-AR (B) and β 3-AR (C). β3-AR shows a significantly higher methylation in normal glucose conditions (p < 0.01). (D) shows terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay that demonstrates a significantly high (p < 0.005) apoptosis of retinal endothelial cells grown in hyperglycemia. (E, F and G) show Dichlorodihydrofluorescein diacetate (DCFH-DA) assay showing a high production (p < 0.001) of reactive oxygen species (ROS) in retinal endothelial cells that were grown in high glucose (25 mM) condition (F), while low production in cells grown in normal glucose (5 mM) condition (G). 8-OHdG level in high and normal glucose (H) where H2O2 was used as control.