Associations between post-bariatric surgery gut microbiota changes and type 2 diabetes remission: a narrative review

Bariatric surgery is accompanied by substantial remodeling of the gut microbiota, which has been associated with type 2 diabetes mellitus (T2DM) remission. This review summarizes evidence from recent years on how surgery-induced microbial changes contribute to metabolic improvement. Key findings include a sustained increase in beneficial bacteria such as Akkermansia muciniphila and short-chain fatty acids (SCFAs)-producing taxa, coupled with a decrease in proinflammatory organisms. These shifts enhance intestinal barrier function, reduce systemic inflammation, modulate immune responses, and alter bile acid metabolism and SCFAs signaling-collectively improving glucose homeostasis and insulin sensitivity. We conclude that gut microbiota restructuring is a plausible contributor to the metabolic benefits of bariatric surgery, offering insights for future microbiome-targeted therapies in T2DM.