Effects of Tannic Acid on Gut Microbiota and Metabolomics in Mice with Type 2 Diabetes

Tannin, a mixture of polyphenols, has been shown to possess various pharmacological activities, including antitumor, hypolipidemic, and hypoglycemic effects. Currently, tannic acid has demonstrated beneficial effects in improving the streptozotocin-induced type2 diabetes model. However, the specific mechanisms by which tannic acid lowers blood glucose through modulation of the gut microbiota and metabolomics remain to be fully elucidated. This study investigated the therapeutic effect of tannic acid from Galla Chinensis on mice with type 2 diabetes (T2D) induced by a high-fat diet (HFD) and streptozotocin (STZ). To explore the potential mechanisms, we conducted 16S diversity analysis of gut microbiota and non-targeted metabolomics analysis. Our findings demonstrate that appropriate administration of tannic acid significantly reduces fasting blood glucose levels and alleviates pathological changes in the liver and islets. The results indicate that tannic acid promotes the growth of beneficial bacteria and inhibits harmful bacteria. Furthermore, tannic acid improves diabetes and its complications mainly through glycerolphospholipid metabolism and arachidonic acid metabolism.