a, b Total BAs and total HCA species serum concentrations before and after gastric bypass surgery in all (n = 38), male (n = 18) and female (n = 20) patients with obesity and diabetes. c Serum concentrations of total and individual HCA species before and after surgery. d BMI and glycemic markers before and after surgery. e ROC analysis of the changes (12 months vs. baseline) of total and individual HCA species. f–k The serum concentrations of total BAs, total HCA species, and individual HCA species at baseline (0 month) in the remission group (n = 26) and the non-remission group (n = 12). Data are expressed as median with interquartile range (a, b, f–k), mean with SE (c) and mean with SD (d). * indicates statistical significance (p < 0.05) based on (a–d) two-sided Wilcoxon signed-rank test when compared with baseline (0 month), and (f–k) two-sided Mann–Whitney U test when comparing remission and non-remission groups.