3.4.1. Internal Validation
To verify the diagnostic efficiency of the model, the sensitivity and specificity of different cutoff points were calculated. In the internal validation group, when the cutoff point was 2, the sensitivity of the diagnosis of DN reached 0.957, the specificity was 0.725, and the Jordan index was 0.682. When the cutoff point was 4, the specificity of the diagnosis of DN reached 1. By drawing the ROC curve, AUC = 0.924 (