The paper preprocesses the data including basic information, admission and discharge record and progress note of diabetes Electronic Medical Records(EMR), implementing decision tree, Artificial Neural Network(ANN), Naive bayesian and K-Nearest Neighbor(KNN) classifications respectively on data that have been processed with Weka 3.9. The result shows that Naive bayesian classification, which is superior to the others in predicting and classifying such data, can provide basis for the classification and prediction of diabetes.