Published online Dec 26, 2020. doi: 10.12998/wjcc.v8.i24.6213
Peer-review started: July 13, 2020
First decision: September 30, 2020
Revised: October 13, 2020
Accepted: November 2, 2020
Article in press: November 2, 2020
Published online: December 26, 2020
Processing time: 159 Days and 13.5 Hours
The prevalence of colorectal cancer (CRC) and type 2 diabetes mellitus (T2DM) is increasing globally. It is rarely noticed that the incidence of CRC is higher in patients with T2DM. What needs to be mentioned is that metformin, a commonly used clinical drug for T2DM, attracts scholars’ attention because of its benefits in lowering the risk of developing CRC. Hence, we try to find the common grounds of initiation of T2DM and CRC and the reason why metformin reduces the risk of CRC in patients with T2DM. We noticed consistent changes of gut microbiota, such as elevated Bacteroides, Prevotella and Bifidobacterium and depressed Firmicutes and Lactobacillus. Furthermore, many studies in recent years have proved that the efficacy of metformin, such as improving blood glucose, depends on the gut microbiota. Coincidentally, the progression of CRC is inseparable from the contributions of gut microbiota. Therefore, we first proposed the concept of the metformin-gut microbiota–CRC (in T2DM) axis to explain the effect of metformin in reducing CRC in patients with T2DM. In this review, we elaborated the new concept and its potential clinical application value.
Core Tip: Metformin has been found to reduce colorectal cancer in patients with type 2 diabetes, but the mechanism is unknown. Studies have confirmed that gut microbiota is not only closely related to type 2 diabetes and colorectal cancer, but also mediates the effects of metformin. Therefore, we proposed the concept of the metformin-gut microbiota-colorectal cancer axis in type 2 diabetes mellitus. The concept also provides new ideas for clinical drug use, clinical cancer treatment, and clinical application of gut microbiota.