Since human heart tissue is difficult to collect and we could not obtain enough fresh heart tissue to measure the levels of Rol and atRA, we used forensically collected heart sections from T2DM patients to perform immunohistochemistry (IHC) staining of RARs and found that the expression of RARa and RARb were reduced, suggesting that cardiac retinol metabolism disorder may also be present in the hearts of T2DM patients. The gene discussed is RARB; the disease is type 2 diabetes mellitus.