The apolipoprotein E (ApoE) ε4 allele and type 2 diabetes mellitus (T2DM) are independent risk factors for Alzheimer's disease (AD), the most prevalent neurodegenerative disorder in the elderly. The T2DM patients carrying the ApoE ε4 allele exhibit heightened activation of platelet glycogen synthase kinase-3β (GSK-3β), a key downstream kinase in the insulin signaling pathway, along with more severe cognitive deficits. This observation suggests an intrinsic link between ApoE ε4, GSK-3β, and cognitive dysfunction. However, the precise mechanisms by which ApoE ε4 influences GSK-3β activity and exacerbates brain pathology and cognitive decline in T2DM patients remain poorly understood.