Carbohydrate and amino acid metabolism was damaged in T2DM patients (Figure 5), and they were positively correlated with Chao1 and ACE (r = 0.53, p < 0.01: r = 0.56, p < 0.01; r = 0.54, p < 0.01: r = 0.58, p < 0.01). Here, ACE is linked to type 2 diabetes mellitus.