Gut microbes again linked to diabetes -- but geography matters

An electron microscope scan of bacteria in the intestines of a mouse. Researchers are learning more about how microbes in the digestive system influence health.

Particular combinations of bacteria in the human digestive system can identify patients who have or are likely to develop Type 2 diabetes, scientists reported Wednesday in the online edition of the journal Nature.

But the precise combinations of microbes that influence development of the disease may vary among patients of different ages, sexes and ethnicities, the Swedish and Danish researchers said — which means that more study will be needed to use bacteria to diagnose diabetes in people everywhere.

The Scandinavian team, including senior author Fredrik Backhed of the University of Gothenburg in Sweden, collected bacterial DNA from fecal samples from 145 70-year-old women. Their sample was divided into three similarly sized groups: 53 women who had Type 2 diabetes, 49 with impaired glucose tolerance (a precursor to full-blown diabetes) and 43 who were healthy.

Like all humans, each of those women had thousands of microbial species living in her intestines. The scientists looked at all of the DNA from all of the microbes concurrently, in a technique known as metagenomic analysis. Analyzing what they found and identifying DNA sequences that acted as signatures of particular genes, the team was able to determine that the women with Type 2 diabetes were more likely to have certain combinations of microbes in their guts: lower numbers of bacteria that produce the chemical butyrate, which is believed to play a role in glucose and fat metabolism, for instance. Prediabetic women and healthy women also had characteristic microbial profiles.


The group was also able to use its metagenomic model to predict which women had a diabetes-like metabolism. The approach produced risk scores that were similar to those generated by established systems looking at other risk factors involved in diabetes development, the authors wrote.

In an article that accompanied the study, diabetes researchers Willem de Vos of Wageningen University in the Netherlands and Dr. Max Nieuwdorp of the Amsterdam Medical Centre wrote that studying microbes could give scientists a way to identify “early warning signals” as a patient’s metabolic function falters.

The new study follows a similar analysis of Type 2 diabetes patients in 2012, also published in Nature, which looked at microbiota in 345 Chinese men and women. While there were similarities in the gut microbes of diabetic and healthy study subjects in Europe and in Asia, there were also some significant differences, which suggests that doctors might need to use gut microbe-based tests for Type 2 diabetes that are different for different types of patients.

De Vos and Nieuwdorp wrote that further study might help researchers figure out ways to use intestinal microbiota to diagnose, or even treat, Type 2 diabetes.

“Such studies might lay the foundation for designing therapeutic bacteria that can be used to ‘reset’ the intestinal microbiota to the composition that is characteristic of healthy individuals,” they wrote. “The goal of manipulating our microbiota to keep disease at bay could be closer than we think.”

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