The link between polymorphic genes involved in redox homeostasis, such as GCLM (rs2301022), GGT7 (rs6119534, rs11546155), GSTM1 (+/del), GSTP1 (rs1695, rs1138272), RAC1 (rs7784465), and CYBB (rs5917471), and type 2 diabetes differs in overweight and normal-weight individuals. The gene discussed is GSTP1; the disease is type 2 diabetes mellitus.