DPP4 and Insulin resistance: Although there was a significant difference in reduction of BMI (p < 0.001), FBS (p = 0.004), and insulin resistance (p = 0.019) before and after the surgery (Table 3 and Supplementary Figures 2A,B), we did not find any corresponding difference in plasma DPP4 activity (p = 0.084) and levels (p = 0.163) (Table 3 and Supplementary Figures 2C,D).