1159-P: Metformin Monotherapy Changes Gut Microbiota in Newly Diagnosed Type 2 Diabetes

Current clinical guidelines suggest metformin as the first-line therapy to treat type 2 diabetes. Despite its use for over 60 years, the precise mechanisms of metformin are still not fully discovered. Traditionally, liver was thought to be the main target of metformin action. More recently, gut has become the center of attention due to the increasing evidences suggesting the antidiabetic effect of metformin is derived from the gut. We aimed to evaluate the antidiabetic effects of metformin and the changes of gut microbiota in newly-diagnosed and drug-naive type 2 diabetes. We recruited 22 patients with newly-diagnosed and drug-naive type 2 diabetes from the outpatient clinic in a university hospital in southern Taiwan. Before and after metformin monotherapy for three months, we collected the biochemical data and measured fecal microbiota by quantitative real-time PCR with 16S rRNA gene sequencing. At the end of three months, there were totally 14 patients continued on metformin monotherapy and completed the collection of stool samples. Our results discovered that body-mass index, HbA1C, and fasting blood glucose decreased while HDL-C increased significantly after metformin monotherapy for three months. There were no significant changes in cholesterol, triglyceride, LDL-C, and HOMA-IR. Using quantitative real-time PCR with 16S rRNA gene sequencing, we found that Akkermansia and Escherichia increased significantly. The two major phylum of Firmicutes and Bacteroidetes did not have significant changes after three-month metformin monotherapy. We revealed that the antidiabetic effects of metformin associated with the changes of microbiota including Akkermansia and Escherichia. Understanding the interaction between metformin and gut microbiota in newly-diagnosed type 2 diabetes can help to identify important microbiota species related to the antidiabetic effect of metformin. In the future, gut microbiota has the potential to serve as a new therapeutic tool or target in treating type 2 diabetes.