The role of gut bacteria in sustained diabetes improvement

Changes in gut microbiota after bariatric surgery are strongly linked to altered metabolic health and sustained improvement in type 2 diabetes, according to a study led by researchers at the University of Gothenburg.

Bariatric surgery is an effective treatment for obesity and type 2 diabetes, but patient outcomes vary widely. The current study, published in Nature Metabolism, suggests that the variations are partly explained by differences in how the composition of gut bacteria changes after surgery.

By analyzing gut microbiota before and after the most common procedures, gastric bypass and sleeve gastrectomy, the study identifies microbial features associated with improved glucose metabolism and tracks changes in glycemic control for up to five years post-surgery.

More specifically, the study shows that changes in gut bacterial composition and function, and not just weight loss, are associated with important metabolic improvements, including insulin release and blood sugar control.

The gut ecosystem reshaped

Patients with type 2 diabetes who achieved improved glycemic control exhibited greater microbial gene richness and an enhanced capacity for fermentation processes, including the production of butyric acid.

Bariatric surgery reshapes the gut ecosystem in diverse ways, and when this remodeling results in greater bacterial diversity, it is often associated with improved metabolic health. These findings highlight the importance of considering microbial ecology when evaluating treatment responses."

Valentina Tremaroli, Microbiologist, University of Gothenburg

Applying high-resolution metagenomics alongside integrative data analysis enables more robust and comprehensive insights, allowing researchers to pinpoint specific microbial genes linked to diabetes remission.

"These methods move beyond purely descriptive analyses, uncovering reproducible patterns in the composition of gut microbial genes that can inform future precision medicine strategies," says Lisa Olsson, bioinformatician and researcher at the University of Gothenburg.

Suggests active role of gut bacteria

The two surgical procedures produced broadly similar changes, but there were differences. Gastric bypass produced more uniform changes in the gut microbiome, while gastric sleeve produced a more individualized response.

"Our results suggest that the gut microbiome is not just a bystander, but can actively contribute to diabetes remission after bariatric surgery. Importantly, this also indicates that targeting the microbiome, through diet, probiotics or other interventions, could potentially enhance or even replicate some of the beneficial metabolic effects of surgery," says Fredrik Bäckhed, professor at the University of Gothenburg.