ε3/4 genotype of the apolipoprotein E is associated with higher risk of Alzheimer's disease in patients with type 2 diabetes mellitus

Abstract As a progressive and chronic disease, type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia with rising prevalence worldwide. The e4 allele of the apolipoprotein E (ApoE) gene may be risk factor of severe peripheral neuropathy in T2DM patients. The association of ApoE polymorphism and Alzheimer's disease (AD) in T2DM patients remains largely unknown. Totally 156 T2DM patients with AD and 145 T2DM patients were included. The genotypes and allele frequency of ApoE were analyzed to explore the role of ApoE in AD in T2DM patients. The levels of total cholesterol (TC), triglyeride (TG), low density lipoprotein-cholesterol (LDL-C), and high density lipoprotein-cholesterol (HDL-C) were detected to further investigate mechanism of ApoE. Genotype frequency ratio of genotype e3/4, e4/4 and allele e4 among the T2DM patients with AD was obviously increased. The TC, TG and LDL-C levels of T2DM patients with e3/4 genotype were higher than those with e3/3 or e2/3 genotype and the e3/4 genotype, while the HDL-C level was on the contrary, suggesting that e3/4 genotype elevated blood lipid levels in T2DM patients with AD, thus increasing the risk of AD in T2DM patients. ApoE polymorphism was associated with AD in T2DM patients. ApoE e3/4 genotype was possibly to serve as a risk factor for AD in T2DM patients by enhancing the blood lipid levels.