GGT1 and type 2 diabetes mellitus: Among the genes related to the antioxidant system, genetic variants associated with T2DM were peroxiredoxin 6 (PRDX6_rs150751487), GPX1_rs1050614, GPX3_rs8177426, glutathione S-transferase alpha 5 (GSTA5)_rs7739421, GSTA5_rs2397118, glutamate–cysteine ligase catalytic subunit (GCLC)_rs74515451, GCLC_rs78386169, glutathione disulfide reductase (GSR)_rs10274638, and gamma-glutamyltransferase 1 (GGT1)_rs2076999.