Among them, OPTN is the only differentially expressed protein correlated with all three factors (i.e., decreased MMSE score, increased Aβ1‐42/Aβ1‐40 and rGSK‐3β), and elevation of OPTN showed a strong power in discriminating T2DM‐MCI from T2DM‐nMCI patients. The gene discussed is OPTN; the disease is type 2 diabetes mellitus.