What is already known on this topic
About one in 14 adults worldwide are estimated to have prediabetes, a condition characterized by abnormal levels of sugar in the blood and insulin resistance, which predispose people to develop type 2 diabetes. Previous studies suggested that gut microbes could contribute to type 2 diabetes, but these studies have included individuals on anti-diabetic drugs such as metformin, which can alter the gut microbiota.
What this research adds
Researchers analyzed the microbiota of nearly 1,500 Swedish people who had never been treated for diabetes. The gut microbiota was altered in people with impaired glucose tolerance and type 2 diabetes, regardless of whether people were treated with metformin or other drugs. The abundance of potentially beneficial bacteria was reduced in people with prediabetes and those with type 2 diabetes.
The findings suggest that the gut microbiota could be targeted to prevent the development of type 2 diabetes.
About one in 14 adults worldwide are estimated to have prediabetes, a condition characterized by abnormal levels of sugar in the blood and insulin resistance, which predispose people to develop type 2 diabetes. Now, researchers have found that alterations in the gut microbiota composition in prediabetic people could contribute to type 2 diabetes.
The findings, published in Cell Metabolism, suggest that the gut microbiota could be targeted to prevent the condition. They could also help to predict who will develop type 2 diabetes based on their gut microbiota. “Our study shows clearly that the composition of the gut microbiota may have a great potential for helping us to understand the risks of developing type 2 diabetes, and therefore improve our chances of detecting, preventing and treating the disease,” says study lead author Fredrik Bäckhed at the University of Gothenburg.
Previous studies suggested that gut microbes could contribute to type 2 diabetes, but these studies have included individuals on anti-diabetic drugs such as metformin, which can alter the gut microbiota. To rule out the possibility that the gut microbiota was affected by the condition or its treatment, Bäckhed and his colleagues analyzed 1,011 people who had not yet developed type 2 diabetes.
Lacking beneficial bacteria
Compared to healthy people, individuals with prediabetes had an altered gut microbiota. Those with impaired fasting glucose showed the least differences, whereas people with impaired glucose tolerance showed more pronounced changes in the microbiota composition.
The researchers also found that people with prediabetes as well as those recently diagnosed with type 2 diabetes, but yet to begin any treatment, had lower levels of butyrate-producing gut microbes such as Clostridiales bacterium, Flavonifractor plautii, Coprococcus eutactus, Alistipes obesi, and Intestinimonas butyriciproducens.
Butyrate is a fatty acid that controls inflammation and is produced by beneficial bacteria in the gut as they digest dietary fibers. Previous studies have suggested that people with diabetes have substantially lower levels of butyrate-producing bacteria than healthy individuals. Taken together, the results of the study suggest that increasing signs of diabetes are accompanied by decreasing levels of butyrate-producing bacteria.
Although the researchers confirmed their findings in a second group of 484 Swedish people, they say that more work is needed to understand whether changes in microbiota composition directly cause the metabolic problems or whether the microbiota is simply responding to the metabolic disease.
“We hope to find patterns and identify which components of the gut microbiota identify individuals whose risk of developing type 2 diabetes is elevated,” Bäckhed says. “In the future, perhaps we’ll be able to prescribe individualized dietary changes, or develop new types of probiotic that can prevent or perhaps even treat the disease.”