To develop a traditional Chinese medicine （TCM） diagnostic scale for type 2 diabetes mellitus with turbid-toxin accumulation syndrome and to validate the performance of the scale. A candidate pool was established through literature review and expert consultation， and a clinical case information collection form was developed accordingly. Patients with type 2 diabetes mellitus admitted to the First Teaching Hospital of Tianjin University of Traditional Chinese Medicine from July 2021 to January 2022 were investigated， and 312 valid clinical case information collection forms were obtained， which were randomly divided into 235 cases in the study group and 77 cases in the validation group. Four statistical methods， namely， differentiation analysis， Cronbach's coefficient， correlation coefficient， and stepwise regression， were used to screen out the candidate items， and Logistic regression analysis and factor analysis were used to assign weights to the items， and the final diagnostic model was determined by the receiver operating characteristic （ROC） curve， and the diagnostic thresholds were calculated for the Yoden index. The final TCM diagnostic scale for type 2 diabetes mellitus was composed of 8 items： turbid dirt coating （with a weight value of 23， the same below）， sticky stools （16）， fullness in the epigastrium and abdomen （12）， dark complexion （12）， irritability （11）， brown spots on the skin （11）， heaviness of head （10）， and chest stuffiness （5）， and the degree score was 0， 0.5， 1.0， and 1.5 points corresponding to no， mild， moderate and severe symptoms， respectively. The total score was the sum of the degree score multiplied by the weighted value of each item， and when the total score reached 33 points， it is diagnosed as the turbid-toxin accumulation syndrome. The established scale was tested and evaluated in the study group and the validation group， and the results showed that the sensitivity of the study group and the validation group was 89.38% and 89.47%， with the specificity of 95.90% and 89.74%， the Yoden index of 0.85 and 0.79， the positive predictive value of 95.28% and 89.47%， the negative predictive value of 90.70% and 89.74%， the diagnostic advantage ratios of 198.18 and 72.67， and the Kappa values of 0.86 and 0.79， which indicated that the TCM diagnostic scale for turbid-toxin accumulation syndrome of type 2 diabetes mellitus showed good diagnostic ability.