CONTEXT: Bile acids and fibroblast growth factor 19 (FGF19) have been suggested as key mediators of the improvements in glucose metabolism after Roux-en-Y gastric bypass (RYGB).

OBJECTIVE: To describe fasting and postprandial state total bile acid (TBA) and FGF19 concentrations before and after RYGB and relate them to parameters of glucose metabolism, GLP-1, CCK and cholesterol fractions.

DESIGN & SETTING: Prospective descriptive study, performed at the Department of Endocrinology, Hvidovre Hospital, Hvidovre, Denmark.

PATIENTS: 13 type 2 diabetic (T2D) patients and 12 normal glucose tolerant (NGT) subjects.

INTERVENTION: Four-hour liquid meal test performed before, 1 week, 3 months and 1 year after RYGB.

MAIN OUTCOME MEASURES: Fasting and postprandial TBA and FGF19 concentrations.

RESULTS: Fasting TBA concentrations decreased in NGT subjects (p<0.001) and were unchanged in T2D patients one week after surgery, but then increased gradually in both groups with time from surgery (ANOVA ptime<0.001). AUC TBA was decreased in NGT subjects 1 week after RYGB (pre: 567 mmol x min/L [481-826], 1wk: 419 [381-508], p=0.009) and unchanged in T2D patients (894 [573-1002], 695 [349-1147]; p=0.97) but then increased with time from surgery in both groups (ptime<0.001). Fasting FGF19 concentrations were unchanged acutely after RYGB (NGT: 140 pg/mL [100-162]; 134 [119-204], p=0.42; T2D: 162 [130-196], 154 [104-164], p=0.68) and remained unchanged throughout the follow-up period. AUC FGF19 increased gradually with time after surgery (ptime<0.001), resembling the changes seen with AUC TBA. One week after RYGB, glucose metabolism improved, LDL- and HDL-Cholesterol decreased, CCK and GLP-1 secretion increased, whilst FFA concentrations were unchanged.

CONCLUSION: TBA and FGF19 do not explain acute changes in glucose metabolism, cholesterol fractions and gut hormone secretion after RYGB.