Underscoring potential clinical and therapeutic relevance, previous studies have shown that bile acid concentrations are altered in patients with T2D,27 28 and treatment with bile acid sequestrants affects glucose metabolism.29 Moreover, bile acids are thought to increase intestinal transit through takeda G protein-coupled receptor 5 (TGR5),30 which is in line with our finding that transit time correlated inversely with faecal isolithocholic acid (figure 5A). This evidence concerns the gene XCR1 and type 2 diabetes mellitus.