INS and early-onset autosomal dominant Alzheimer disease: Thus an increased level of O-GlcNAcylation on proteins along the insulin signalling pathway has been proposed to be involved in insulin sensitivity,4,5 and hyper-phosphorylation of the microtubule-associated protein tau that marks the development of the Alzheimer disease was shown to be reciprocal with the abnormally low O-GlcNAcylation.6