The expression of OGT and glutamine-fructose-6-phosphate amidotransferase (GFAT), the first and rate-limiting enzyme in the synthesis of UDP-GlcNAc, are significantly increased in the liver of T2D patients, indicating higher levels of O-GlcNAc (Fig. 9d). This evidence concerns the gene GFPT2 and type 2 diabetes mellitus.