Combined effect of Scutellaria baicalensis with metformin on glucose tolerance via gut microbiota modulation in type 2 diabetes patients

Aims: Metformin is common medicine and Scutellaria baicalensis (SB) is herb for treatment of type 2 diabetes (T2D). Gut microbiota is in the limelight to predict, prevent and treat metabolic disease including T2D via modulating intestinal bacteria composition. The purpose of this study was to investigate the effect of herbal medicine (SB) combined with metformin on treatment of T2D with evaluating the modulation of gut microbiota composition.Materials and methods: The T2D patients were randomized into control and treatment groups. The treatment group was taken SB (3.52g/day) or placebo maintaining prescribed dose of metformin for 8 weeks, and then cross-over for 8 weeks after wash-out period for 4 weeks. The effects of SB and placebo on the intestinal microbiota were evaluated by metagenomic analysis.Results: Glucose level at 1 hour and AUC during OGTT were lower in SB group compared to placebo. Similarly, the relative RNA expression level of TNFa was significantly reduced after SB treatment. In addition, SB treatment influenced the gut microbiota especially, genus Lactobacillus and Akkermansia remarkably increased after SB treatment. However, some subjects showed high liver enzyme level after SB treatment, their microbiota composition at base-line also differed. Moreover, total 12 taxa were correlated with OGTT indicator. From the metagenomic data, we also predicted the metabolism that selenocompound metabolism was increased, while naphthalene degradation was decreased after SB treatment.Conclusion: These results suggest that SB with metformin treatment may improve the glucose tolerance and inflammation and influence the gut microbiota community in T2D.