There were significant differences (p < 0.05) in age, education, plasma AST/ALT ratio, fasting plasma glucose, gender, smoker, drinker, hobby, MMSE scores and MoCA scores between AD, aMCI and the normal group, while there was no significant difference (p > 0.05) in BMI, triglyceride, cholesterol, high density lipoprotein, low density lipoprotein, take exercise, hypertension, diabetes, hyperlipidemia, heart disease, and APOE E4 among the three groups. The gene discussed is APOE; the disease is diabetes mellitus.