Objective To explore the mediating effect of triglyceride-glucose(TyG)index on the risk of proteinuria in patients with type 2 diabetes mellitus(T2DM).Methods 734 patients with T2DM who underwent routine physical examination in Quyang Road Community Health Service Center,Shanghai from March 2023 to May 2023 were enrolled.The results of basic information,biochemical indicators,abdominal ultrasound and other results were collected.All patients were divided into the normal group,microproteinuria group,and massiveproteinuria group,and stratification analyses were underwent according to glycated hemoglobin(HbA1c),body mass index(BMI),TyG index,and presence or absence of non-alcoholic fatty liver disease(NAFLD).Factors affecting proteinuria in T2DM patients were analyzed.Multivariate logistic regression was used to analyze the impact of TyG index and NAFLD on proteinuria in type 2 diabetes population.Regression coefficient sequential test was used to analyze whether TyG mediates NAFLD associated proteinuria.Results There were statistically significant differences in age,BMI,urinary creatinine,HbA1c,TyG index,etc.among the normal group,microproteinuria group,and massiveproteinuria group(all P＜0.05);there was no statistically significant difference in gender among the three groups.Multivariate logistic regression analysis showed that taking the HbA1c＜7％and BMI＜24 kg/m2 group as a reference,the patients with HbA1c≥7％and BMI≥24 kg/m2 had the highest risk of proteinuria(P=0.022),followed by the HbA1c≥7％and BMI＜24 kg/m2 group(P=0.039).Taking the TyG index(7.65-8.69)as a reference,the risk of proteinuria in the(9.45-11.90)group was 3.321 times(P＜0.001).The mediation effect analysis showed that the TyG mediated NAFLD associated proteinuria(P＜0.001),with the mediation effect accounting for 55.70％of the total effect.Conclusion TyG index may be an independent risk factor for proteinuria in patients with T2DM,and the prevalence of proteinuria is high in patients with poor control in HbA1c and excessive BMI,and TyG may partially mediate the risk of proteinuria in patients with T2DM.