In particular, the association of the most extensively studied deletion (null) polymorphisms in GST mu 1 (GSTM1) and GST theta 1 (GSTT1) genes, which results in a complete lack of corresponding enzymes [17], has been described to be involved in T2DM development and diabetes-related complications [18,19]. This evidence concerns the gene GSTM1 and type 2 diabetes mellitus.