Further analysis revealed that serum levels of GSH, SOD and nesfatin-1 in T2DM or prediabetes with impaired HOMA-β values (under the cut-off) were apparently low (P < 0.001, P = 0.006, P < 0.001, respectively, in T2DM; P < 0.001, P < 0.001, P < 0.001, respectively, in prediabetes), compared to those patients with normal HOMA-β values (equal to or above the cut-off). The gene discussed is SOD1; the disease is type 2 diabetes mellitus.