OGT and Insulin resistance: Another evidence of the involvement of O-GlcNAcylation in insulin resistance was obtained in transgenic mouse models when GFAT and OGT were overexpressed in muscle and adipose tissue, which use the same glucose promoter GLUT4, and observing disturbances in energy metabolisms, such as insulin resistance and hyperleptinemia, characteristics also observed in diabetic patients (Love and Hanover, 2005).