Background Insulin resistance (IR) plays an important pathophysiological role in the development of diabetes,dyslipidemia,hypertension,and cardiovascular disease.Moreover,IR can occur even in non-obese people without diabetes.However,direct detection of IR is complicated.In order to find a simple surrogate marker of IR early in nonobese people,we investigate the association of commonly-used biochemical markers (liver enzymes and lipid profiles) with IR in urban middle-aged and older non-obese Chinese without diabetes.Methods This cross-sectional study included 1 987 subjects (1 473 women).Fasting blood samples were collected for measurement of glucose,insulin,liver enzymes,lipid profiles and creatinine.Subjects whose homeostasis model of assessment-IR (HOMA-IR) index values exceeded the 75th percentile (2.67 for women and 2.48 for men) of the population were considered to have IR.The area under the receiver operating characteristic curve (ROC) was used to compare the power of potential markers in identifying IR.Results Triglycerides (TG) and ratio of TG to high-density lipoprotein cholesterol (TG/HDL-C) discriminated IR better than other indexes for both sexes; areas under the receiver operating characteristic (ROC) curves (AUC) values were 0.770 (95％ confidence interval 0.733-0.807) and 0.772 (0.736-0.809),respectively,for women and 0.754 (0.664-0.844)and 0.756 (0.672-0.840),respectively,for men.To identify IR,the optimal cut-offs for TG and TG/HDL-C ratio were 1.315 mmol/L (sensitivity 74.3％,specificity 71.0％) and 0.873 (sensitivity 70.1％,specificity 73.4％),respectively,for women,and 1.275 mmol/L (sensitivity 66.7％,specificity 74.4％) and 0.812 (sensitivity 75.8％,specificity 69.2％),respectively,for men.Conclusion TG and TG/HDL-C ratio could be used to identify IR in urban middle-aged and older non-obese Chinese without diabetes.