Ahlin S, et al. - Following biliopancreatic diversion (BPD) and Roux-en-Y gastric bypass (RYGB), researchers explored if improvement in insulin sensitivity and concentration of circulating bile acids were related. In this prospective observational study, the sample consisted of nine patients who had BPD and six who had RYGB. Participation inclusion criteria were a BMI exceeding 40 kg/m², no prior diagnosis of type 2 diabetes, and readiness to engage. Major endocrine diseases, malignancies and liver cirrhosis were the criteria for exclusion. After both BPD and RYGB surgery, plasma levels of total bile acids increased with a clear improvement in insulin sensitivity, which was was closely linked to (and predicted by) increases in secondary conjugated bile acids, especially glycodeoxycholic acid (GDCA). After metabolic surgery, GDCA may drive improved insulin sensitivity.