MCAT and diabetes mellitus: Many common polymorphisms have been found in the human MT gene region.[9] Polymorphisms of the MT1A, MT1B, and MT2A genes have been significantly associated with metabolic abnormalities including type 2 diabetes mellitus and hyperlipidemia.[10,11] Thus, MTs may play preventive roles in the protection against metabolic disorders, and polymorphisms can affect the protein functions and/or the expression level of MTs.