Abnormal glucose metabolism includes diabetes mellitus, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG). A growing number of studies is showing that abnormal glucose metabolism may correlate with cognitive impairment, and increase the risk of Alzheimer’s disease (AD) at the same time. The abnormal glucose metabolism-related cognitive impairment may be associated with insulin resistance, blood-brain barrier transport of glucose disorders, and high glucose toxicity. Epigenetics is the study of heritable changes in gene expression or cellular phenotype caused by mechanisms other than changes in the underlying DNA sequence. The latest study found that improving insulin resistance and intervention at epigenetic aspects can prevent abnormal glucose metabolism-related cognitive impairment.