An increase in the Akkermansia spp. population induced by metformin treatment improves glucose homeostasis in diet-induced obese mice

Background Recent evidence indicates that the composition of the gut microbiota contributes to the development of metabolic disorders by affecting the physiology and metabolism of the host. Metformin is one of the most widely prescribed type 2 diabetes (T2D) therapeutic agents. Objective To determine whether the antidiabetic effect of metformin is related to alterations of intestinal microbial composition. Design C57BL/6 mice, fed either a normal-chow diet or a high-fat diet (HFD), were treated with metformin for 6 weeks. The effect of metformin on the composition of the gut microbiota was assessed by analysing 16S rRNA gene sequences with 454 pyrosequencing. Adipose tissue inflammation was examined by flow cytometric analysis of the immune cells present in visceral adipose tissue (VAT). Results Metformin treatment significantly improved the glycaemic profile of HFD-fed mice. HFD-fed mice treated with metformin showed a higher abundance of the mucin-degrading bacterium Akkermansia than HFD-fed control mice. In addition, the number of mucin-producing goblet cells was significantly increased by metformin treatment (p