This review briefly describes currentconcepts in mechanisms linking DM and insulin resistance/deficiency to AD.Insulin/insulin-like growth factor (IGF) resistance can contribute toneurodegeneration by several mechanisms which involve: energy and metabolismdeficits, impairment of Glucose transporter-4 function, oxidative andendoplasmic reticulum stress, mitochondrial dysfunction, accumulation of AGEs,ROS and RNS with increased production of neuro-inflammation and activation ofpro-apoptosis cascade. The gene discussed is IGF1; the disease is Alzheimer disease.