GGCT and type 2 diabetes mellitus: This hypothesis is supported by our [31,32,33,34,35] and some other [36,37,38] studies which have revealed that single nucleotide polymorphisms (SNPs) at genes encoding glutathione-metabolizing enzymes such as catalytic and modifier subunits of glutamate cysteine ligase, gamma-glutamyl cyclotransferase, glutathione S-transferases (mu, pi, and theta classes), gamma-glutamyltransferase-6 and glutathione peroxidase-1 substantially contribute to type 2 diabetes’ susceptibility.