Role of gut microbiome in regulating the effectiveness of metformin in reducing colorectal cancer in type 2 diabetes

Figure 1 The potential metformin-gut microbiota-colorectal cancer axis in type 2 diabetes mellitus. (1) Metformin may change the gut microbiota after entering the intestine. The changed gut microbiota has cascade reactions to affect tumorigenesis, including reducing inflammation, regulating immunity, and producing metabolites, such as bile acid and genetic toxins. (2) Metformin may play a pharmacological role to influence cancer-related systems in colorectal epithelial cells in the presence of gut microbiota. CDT: Cytolethal distending toxin; SCFAs: Short-chain fatty acids.