In diabetes mellitus, however, AR becomes the key rate-limiting enzyme of the polyol pathway that catalyzes glucose conversion to sorbitol with the consumption of β-nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt hydrate (NADPH), resulting in cellular osmolarity and redox imbalances; AR, thus, mediates tissue and vascular damage [10,11]. This evidence concerns the gene AR and diabetes mellitus.