Objective:To analyze the correlation between related indexes of serum lipid and insulin resistance and cognitive impairment in middle-aged and elderly people with mild cognitive impairment (MCI).Methods:In this cross-sectional study, 262 middle-aged and elderly patients with a Montreal Cognitive Function Scale (MoCA) cognitive score greater than or equal to 18 points who underwent physical examination in the Health Management Center of Beijing Tiantan Hospital Affiliated to Capital Medical University from January 1 to July 31, 2021 were selected as subjects. According to the cognitive function and MoCA score, the patients were divided into MCI group (143 cases) and normal cognition group (119 cases). Basic data, fasting blood glucose, triglyceride (TG), total cholesterol, apolipoprotein E(ApoE) genotype and other clinical indicators were collected. Hypothesis test was used to compare the differences in basic data, related indicators of blood lipid and insulin resistance between the two groups. Spearman correlation analysis was used to analyze the correlation between related indicators of blood lipid and insulin resistance and MoCA score in the two groups.Results:The age and the proportion of patients with hypertension, coronary heart disease and diabetes in the MCI group were all significantly higher than those in normal cognition group [(54.83±8.29) vs (50.76±6.34) years, 37.76% vs 31.93%, 4.20% vs 0.84%, 16.08% vs 8.40%] (all P<0.05). The elevation of serum TG ( r=-0.50, 95% CI:-0.88--0.12), TG glucose product index (TyG) ( r=-0.75, 95% CI:-1.29--0.20) and TG to high-density lipoprotein cholesterol ratio (TG/HDL-C) ( r=-0.52, 95% CI:-0.91--0.13) were all negatively correlated with MoCA score (all P<0.05). After adjusting for age and gender, the elevation of TG ( r=-0.39, 95% CI:-0.75--0.31) and TG/HDL-C ( r=-0.43, 95% CI:-0.80--0.05) were both still negatively correlated with MoCA score (both P<0.05). There was no significant correlation between all indexes and MoCA scores in the normal cognition group (all P>0.05). The elevated TG was negatively correlated with MoCA score in the MCI group ( r=-0.70, 95% CI:-1.23-0.16, P=0.017). There was no significant correlation between elevated TG and MoCA score in patients carrying ApoE ε2 and ApoE ε3 genotypes in MCI group (all P>0.05). Conclusion:Elevated related indexes of blood lipids and insulin resistance are negatively correlated with cognitive scores in middle-aged and elderly people with MCI, and it′s more obvious in patients with ApoE ε4 genotype.