Retinal apoptosis plays a critical role in the progression of DR: using a mouse diabetes model, Kim et al. ([133] reported that metformin decreases co-localisation of TUNEL-positive ganglion cells and O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT), carbohydrate-responsive element-binding protein (ChREBP), and thioredoxin-interacting protein, or NF-κB and suppresses interaction between OGT and ChREBP or NF-κB. This evidence concerns the gene OGT and diabetes mellitus.