The bioinformatics data together indicate that upregulation of SERPINA1, VCP, PRNP, CIP2A, HSPA9, and UQCRC2 and downregulation of IGFBP3, CRHBP, PEPD, and GUSB were correlated to cognitive decline in T2DM patients (Figure 3E). Here, PEPD is linked to type 2 diabetes mellitus.