Several studies have identified specific polymorphisms in antioxidant enzymes that are linked to T2DM risk, including homozygote deletion of GSTM1, heterozygote deletion of GSTT1, GSTP1_rs1695 and rs1138272, GCLC_rs12524494, glutamate–cysteine ligase (GCLM)_rs3827715 and rs41303970, glutathione synthetase (GSS)_rs13041792, GSR_rs2551715, GGT7_rs11546155 and rs6119534, gamma-glutamyl cyclotransferase (GGCT)_rs4270, GPX1_rs1050450, GPX2_rs4902346, catalase (CAT)_rs769217, SOD1_rs2234694, SOD2_rs4880, and SOD3_rs2536512 [13]. The gene discussed is GGCT; the disease is type 2 diabetes mellitus.