INS and type 2 diabetes mellitus: The downregulation of RDH10 in the T2DM pancreas may be related to the reduction of β-cells, and when pancreatic β-cells are exposed to hyperglycemia or high-fat environments, the increase of oxidative stress and inflammatory factors may inhibit the expression of RDH10.The downregulation of RDH10 further leads to the reduction of retinoic acid production, which affects the normal function of pancreatic β-cells and the secretion of insulin, further aggravating the deterioration of islet function, creating a vicious circle (Arregi et al., 2016).