Modulation of Gut Microbiota: Potential Mechanism of Diabetes Remission after Bariatric/Metabolic Surgery

ABSTRACT

Advances in genomic processing technology have been applied to the human microbiota and have provided the understanding of the effect of the microbiota in human health and disease. Especially, studies of the gut microbiota have revealed that changes in gut microbiota are related to obesity and the metabolic syndrome. With weight gain, there is an increase in the ratio of Firmicutes to Bacteroidetes. Certain bacteria have increased the ability to ferment dietary substrates, thereby increasing hosts' energy intake and weight gain. After transplantation of microbiota from lean donors, insulin sensitivity of recipients increased along with proliferation of butyrate-producing intestinal microbiota. One important finding after Roux-en-Y gastric bypass is the relative overabundance of Proteobacteria, which is different with the changes seen in weight loss without bypass surgery. Due to the change of microbiota's composition after bypass surgery, the gut environment is changed to unfavorable for energy absorption including decrease of polysaccharide fermentation. Therefore this change may contribute to the improvement of insulin resistance and loss of body weight. According to these results, modifying the gut microbiota through diet, probiotics, fecal transplants, and surgery might be included as therapeutic options for the diseases linked to imbalance in the microbiota.