XDH and diabetes mellitus: ARC: age-related cataract; HT: hypertension; DM: diabetes mellitus; XO: xanthine oxidase; MPO: myeloperoxidase; LLF: lipofuscin-like fluorophores; MDA: malondialdehyde; SH: thiol; FRAP: ferric reducing/antioxidant power assay; GPx: glutathione peroxidase; SOD: superoxide dismutase.