The excessive oxidative stress produced by abnormalities in glucose metabolism usually found in T2DM patients (Darenskaya, Kolesnikova & Kolesnikov, 2021). It was reported that single nucleotide polymorphisms (SNPs) of genes encoding the antioxidant enzymes, such asglutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and paraoxonase (PON), affect the oxsidative stress (Oh et al., 2007; Min et al., 2006; Senoner & Dichtl, 2019; Abd El Azeem et al., 2021; Wang et al., 2014). The gene discussed is CAT; the disease is type 2 diabetes mellitus.