Type 2 diabetes affects more than 400 million people worldwide. Some studies have demonstrated that the microbes that inhabit the human gut contribute to the pathophysiology of type 2 diabetes, but the use of anti-diabetes drugs like metformin may have confounded the results due to their impact on the gut. Findings from a new study suggest that the overall makeup of the gut microbial population in people with type 2 diabetes is altered.

The authors of the study profiled the microbiota of two groups of participants with varying degrees of glucose tolerance, ranging from normal to impaired (prediabetes) to having untreated type 2 diabetes. One group included 189 people who had isolated impaired fasting glucose, 178 who had isolated impaired glucose tolerance, 75 who had combined glucose intolerance, and 46 who had type 2 diabetes but had not begun treatment. A second group included 523 people with normal glucose tolerance, 226 at low risk for developing type 2 diabetes, and 297 at high risk.

They found that the composition of the gut microbiota among the participants with any degree of glucose intolerance differed markedly from that of the participants with normal glucose tolerance. The participants with prediabetes and diabetes were more likely to have fewer butyrate-producing bacteria in their guts. Butyrate is a short-chain fatty acid produced during bacterial fermentation in the human colon. It has wide-ranging effects on human physiology. The authors also noted that the composition of the gut microbiota can serve as a biomarker for diabetes.

These findings suggest that altering the gut microbiota could serve as a means to prevent the development of type 2 diabetes.

• Link to study abstract.