A clinical cohort study reports that the level of faecal 12-ketoLCA is significantly higher in patients with type 2 diabetes.84 In the keto-BA metabolism pathway, CDCA is converted to 7-ketoLCA by the action of 7alpha- hydroxysteroid dehydrogenase (7α-HSDH), while 12-ketoLCA is metabolized from DCA under the action of 12α-HSDH.83,85 Early studies by Macdonald et al.86 have described the activities of 3α-, 7α- and 12α-HSDH in C. perfringens. Here, HSD17B10 is linked to type 2 diabetes mellitus.