Objective:To explore the mediating effect of carotid atherosclerosis on serum triglyceride-glucose (TyG) index and silent lacunar infarction (SLI) in non-diabetic population.Methods:A total of 2 482 patients were selected from the Health Examination Center of Hebei General Hospital from January 2019 to December 2021. The basic demographic information, biochemical parameters, calculated TyG index and carotid plaque score were collected. SLI was diagnosed according to the criteria formulated by Chinese Society of Neurology. Participants were divided into SLI group and non-SLI group according to whether there was SLI in brain magnetic resonance imaging, and the non-SLI group was normal without lacunar infarction. Spearman correlation analysis was used to explore the correlation between TyG index and carotid plaque score. Binary Logistic regression analysis was used to analyze the effects of TyG index and carotid plaque score on SLI. Bootstrap was used to explore whether carotid plaque score mediated the association between TyG index and SLI.Results:There were 471 patients (18.98%) who had SLI, and 2 011 patients (81.02%) did not. Carotid plaque score [2(0, 5) vs 1(0, 3)] and TyG index [7.17(6.81, 7.64) vs 7.12(6.77, 7.54)] were increased in the SLI group compared with the non-SLI group ( Z=-4.213, Z=-2.636, P<0.05). Spearman correlation analysis showed that carotid plaque score was positively correlated with TyG index ( r=0.083, P<0.001). Multivariate Logistic regression analysis indicated that carotid plaque score ( OR=1.047, 95% CI 1.002-1.094) and TyG index ( OR=1.329, 95% CI 1.106-1.598) were independent risk factors for SLI ( P<0.05). Mediated effect analysis showed that TyG index had a direct effect on the incidence of SLI (β=0.265, 95% CI 0.102-0.428). Carotid plaque score partially mediated the effect of TyG index on the incidence of SLI (β=0.024, 95% CI 0.009-0.043), and the mediating effect accounted for 8.30% of the total effects. Conclusion:In non-diabetic population, TyG index and carotid plaque score are predictors of SLI, and the carotid plaque score is a partial mediator in the effect of TyG index on the incidence of SLI.