Figure 1. Decision trees created by the classification and regression tree (CART) method based on BslI digestion of 16SrRNA gene amplification products from fecal samples. Each operation taxonomic unit (OTU) is named by the combination of a restriction enzyme and restriction fragment length (bp). For example, the BslI 366 bp OTU is designated as B366. The cut-off value for each OTU was calculated from the OTU data of all subjects by the CART method using the Gini coefficient. Similar steps were repeated to construct the decision tree. Node 0 (at the left side of the decision tree) is the root node, namely the starting point for construction of the tree. The decision tree pathways indicate the species, quantities, and OTUs used to divide the different groups of subjects. (a) Decision tree for men. (b) Decision tree for women. non-DM: non-diabetes mellitus group; T1D: type 1 diabetes mellitus group; T2D: type 2 diabetes mellitus group.