Unravelling the hypoglycemic mechanism of Fuzhuan brick tea: insights into intestinal microbiota and metabolites in type 2 diabetes mellitus mice

Fuzhuan brick tea (FBT), a post-fermented tea, has been demonstrated to have an antidiabetic effect. However, evidence of its hypoglycemic effect via gut microbiota and intestinal metabolites has been limited. This work aimed to reveal the potential mechanism of FBT against type 2 diabetes mellitus (T2DM) mice by regulating gut flora and short-chain fatty acids (SCFAs). Thus, we established a T2DM mice model induced by streptozotocin and a high-fat diet, and the 16S rDNA gene sequencing analysed gut microbiota changes, while GC/MS detected SCFAs levels in colonic contents. As a result, after being treated with FBT, the biochemical index of mice revealed significant improvement and the levels of colonic SCFAs were enhanced. Through correlation analysis, the key gut microbiota for the hypoglycemic effect of FBT were identified including Cyanobacteria, Alloprevotella, Erysipelatoclostridium, etc. Additionally, the antidiabetic actions of FBT were mediated by the SCFAs-GPR41/43-GLP-1 pathway and alleviating inflammation related to the increased gut barrier with the tight junction proteins (Claudin-1, Occludin and ZO-1). To sum up, our study provides insights into the possible mechanism of FBT in T2DM and might promote the application of FBT as a potential hypoglycemic agent in the future.