Basic and clinical research has demonstrated that dementia of sporadic Alzheimer's disease (sAD) type is associated with dysfunction of the insulin-receptor (IR) system followed by decreased glucose transport via glucose transporter GLUT4 and decreased glucose metabolism in brain cells.
Defective insulin receptor signalings are associated with the dementia in normal aging and patients with age-related neurodegenerative diseases (e.g., Alzheimer's disease); the cognitive impairment can be reversed with systemic administration of insulin in the euglycemic condition.