IGF1 and Alzheimer disease: Brain insulin/IGF resistance and AD. AD has been associated withdeficits in insulin/IGF signaling due to the effects of insulin/IGF resistance anddeficiency.5 Deficits incerebral glucose utilization have been described in the early stages ofAD.41-44 Suzanne de la Monte and colleagues have proposedthe concept of AD as "Type 3 diabetes".40 They observed an inverse correlation between IR abundanceand the Braak score of AD brains, with 80% reduced IR substrates levels in the mostsevere cases.