MAPT and type 2 diabetes mellitus: In order to reflect the combined effect and to magnify the effect, we performed relative ratios of global O-GlcNAcylation to tau phosphorylation levels, and found that O-GlcNAc/Tau-5, O-GlcNAc/p-S396, O-GlcNAc/p-S404, O-GlcNAc/p-T212, and O-GlcNAc/p-T231 were all decreased in T2DM with MCI subjects in comparison to control subjects (all p < 0.05) (Figure 2).