INS and Hyperglycemia: 1997). Increased UDP‐GlcNAc enhances the activity of OGT (Kreppel and Hart 1999), and hence the increased glucose uptake could be the initiator of increased protein O‐GlcNAcylation after exercise training. Interestingly, contrary to exercise training that has many beneficial effects, pathological nutrient excess and hyperglycemia have also been associated to excessive O‐GlcNAcylation in skeletal muscle (Yki‐Jarvinen et al. 1998; Arias et al. 2004). Yang et al. (2008) linked increased O‐GlcNAcylation of proteins in the insulin signaling pathway to compromised insulin sensitivity.