Gut microbiome can reveal risk of type 2 diabetes

by European Association for the Study of Diabetes

edited by Gaby Clark, reviewed by Robert Egan

Gaby Clark

Scientific Editor

Meet our editorial team
Behind our editorial process

Robert Egan

Senior Editor

Meet our editorial team
Behind our editorial process Editors' notes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

proofread

The GIST Add as preferred source

Changes in the composition of gut bacteria could provide an early warning of type 2 diabetes (T2D), according to new research being presented at the annual meeting of the European Association for the Study of Diabetes (EASD) in Milan, Italy, Sept. 28–Oct. 2.

An analysis of data from hundreds of thousands of people identified hundreds of changes in the composition of the gut microbiome (the community of microorganisms that lives in the gastrointestinal tract) that can be detected before any changes in blood glucose measures.

The findings raise the possibility of using gut microbiome composition to identify people at risk of type 2 diabetes who may benefit most from lifestyle changes. This could support public health efforts to reduce T2D diagnoses, say the study's authors from Italy and the U.K.

Diabetes and prediabetes (where blood sugar levels are higher than normal but not high enough to be classified as diabetes) are diagnosed using tests (HbA1c, fasting plasma glucose and oral glucose tolerance test) that detect elevated blood sugar levels.

However, these tests aren't used to identify people with normal blood sugar levels who are at risk of developing T2D. Instead, risk is assessed using factors like age, sex, BMI and family history.

"These latest findings represent a major step forward in understanding how our gut microbiome is linked directly with metabolic disease," said professor Tim Spector, scientific co-founder of ZOE and one of the study's authors. "Identifying these clear microbial changes before blood sugar levels worsen could lead to earlier intervention with food and lifestyle choices, as well as treatment options, to prevent T2D."

Previous studies have found strong links between T2D and the gut microbiome, but they have not consistently identified the same key bacteria across large populations.

To provide some clarity, Dr. Gabriel Baldanzi of the Laboratory of Computational Metagenomics; professor Nicola Segata, who leads the lab at the CIBIO Department at the University of Trento in Trento, Italy; and colleagues in the U.K. examined metagenomic data (the DNA sequences of the bacteria living in the gut) and health information from more than 200,000 adults in the U.K. and U.S.

The study involved 229,025 people (73.8% female, average age of 50). Of those, 3,627 had T2D and 14,022 had prediabetes. The remaining 211,376 were normoglycemic, meaning they had normal blood glucose levels.

The researchers identified 789 species of bacteria associated with T2D after accounting for age, sex and BMI. Of those, 168 were present at higher levels in people with the condition and 621 at lower levels.

One example, Enterocloster bolteae, was more abundant in people with T2D. This species can form spores and has previously been associated with poorer cardiovascular and metabolic health. Another species, Romboutsia timonensis, was less abundant in people with T2D. This bacterium was first described in the past decade. Some of the other species were uncharacterized, meaning they have never been isolated or cultivated in a lab.

The changes were particularly pronounced in people taking medication for T2D, but they also occurred in those with T2D who were not taking medication.

The team also found that 587 of the 789 species were associated with unmedicated prediabetes.

The researchers then investigated whether the pattern, or signature, was present in people who did not have prediabetes or T2D but were at risk of developing it.

They compared metagenomic data from 135,093 of the normoglycemic people with blood sugar readings taken in the two hours after a meal. Blood sugar temporarily rises after eating. If it remains high, this is usually a sign that the muscles are not responding well to insulin—insulin resistance—an early step on the path to T2D.

People whose blood sugar remained high longer than usual were more likely to have the pattern of gut bacteria seen in T2D. Across the study, the changes in the microbiome became more pronounced as insulin resistance increased.

The researchers say microbiome analysis should not replace the standard tests used to diagnose T2D or prediabetes. Instead, the gut microbiome could offer additional information about a person's risk of T2D, alongside well-known risk factors like sex, age, BMI and family history.

Monitoring changes in the gut microbiome over time could also provide important feedback to people at risk of T2D.

"We know that lifestyle changes, like diet and physical activity, can prevent or delay the onset of T2D," Baldanzi said. "But people often struggle to notice these changes are working, beyond perhaps losing some weight. If we can detect early shifts in the gut microbiome and show someone they are on the right track, that could be a powerful source of motivation to keep going."

"It is important to underline that these results were enabled by the unprecedented size of ZOE's cohort, as well as by the advances we developed in our laboratory in the computational methods needed to interpret metagenomic data," said Segata, the study's corresponding scientist.

"In fact, many bacterial species that are part of the diabetes signature are species that are currently completely uncharacterized and were identified by us for the first time directly from the metagenomic data. In other words, they are new to science."

Key medical concepts

Diabetes Type 2Flora, IntestinalInsulin ResistancePrediabetes

Clinical categories

EndocrinologyCommon illnesses & PreventionGastroenterologyHealthy livingNutrition & Healthy eating Provided by European Association for the Study of Diabetes Who's behind this story?

Gaby Clark

MA in English, copy editor since 2021 with experience in higher education and health content. Dedicated to trustworthy science news. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

Citation: Gut microbiome can reveal risk of type 2 diabetes (2026, September 27) retrieved 28 September 2026 from https://medicalxpress.com/news/2026-09-gut-microbiome-reveal-diabetes.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.