(−)-Epicatechin ameliorates type 2 diabetes mellitus by reshaping the gut microbiota and Gut–Liver axis in GK rats

As one of the most abundant plant polyphenols in the human diet, (−)-epicatechin (EC) can improve insulin sensitivity and regulate glucose homeostasis. However, the primary mechanisms involved in EC anti-T2DM benefits remain unclear. The present study explored the effects of EC on the gut microbiota and liver transcriptome in type 2 diabetes mellitus (T2DM) Goto–Kakizaki rats for the first time. The findings showed that EC protected glucose homeostasis, alleviated systemic oxidative stress, relieved liver damage, and increased serum insulin. Further investigation showed that EC reshaped gut microbiota structure, including inhibiting the proliferation of lipopolysaccharide (LPS)-producing bacteria and reducing serum LPS. In addition, transcriptome analysis revealed that the insulin signaling pathway may be the core pathway of the EC anti-T2DM effect. Therefore, EC may modulate the gut microbiota and liver insulin signaling pathways by the gut–liver axis to alleviate T2DM. As a diet supplement, EC has promising potential in T2DM prevention and treatment.