Oral treatment with Eubacterium hallii improves insulin sensitivity in db/db mice

An altered intestinal microbiota composition is associated with insulin resistance and type 2 diabetes mellitus. We previously identified increased intestinal levels of <i>Eubacterium hallii</i>, an anaerobic bacterium belonging to the butyrate-producing <i>Lachnospiraceae</i> family, in metabolic syndrome subjects who received a faecal transplant from a lean donor. To further assess the effects of <i>E. hallii</i> on insulin sensitivity, we orally treated obese and diabetic <i>db/db</i> mice with alive <i>E. hallii</i> and glycerol or heat-inactive <i>E. hallii</i> as control. Insulin tolerance tests and hyperinsulinemic-euglycemic clamp experiments revealed that alive <i>E. hallii</i> treatment improved insulin sensitivity compared control treatment. In addition, <i>E. hallii</i> treatment increased energy expenditure in <i>db/db</i> mice. Active <i>E. hallii</i> treatment was found to increase faecal butyrate concentrations and to modify bile acid metabolism compared with heat-inactivated controls. Our data suggest that <i>E. hallii</i> administration potentially alters the function of the intestinal microbiome and that microbial metabolites may contribute to the improved metabolic phenotype.