The study suggests that the composition of intestinal bacteria changes during the development of pre-diabetes, and may be a predictor of risk for metabolic diseases such as type 2 diabetes.
Led by Professor Elena Barengolts from the Jesse Brown Veterans Affairs (VA) Medical Center in Chicago, the research team noted that previous research has shown that the gut microbiota can affect human health in many ways and that the mix of this community of microscopic organisms differs in people with type 2 diabetes compared with healthy individuals. However, the new study shows that alterations in the gut microbiota already occur in the early stage of diabetes development known as impaired glucose tolerance or pre-diabetes.
"Your gut bacteria could predict your risk of diabetes," commented Barengolts.
Although the study found connections between composition of the gut microbiota and glycemic states, Barengolts said further research is needed to evaluate whether certain intestinal bacteria cause type 2 diabetes.
However, based on other research her group has conducted, she speculated that the foods we eat affect our diabetes risk through our gut microbiota – adding that if the makeup of the microbiota indeed responsible for the development of type 2 diabetes, it is possible that changing one's gut bacteria could prevent diabetes.
"If doctors accept our suggestions," Barengolts said, "they have additional reasons to recommend foods, such as prebiotics, which improve the growth and activity of helpful gut bacteria."
The research, which is due to be presented at the Endocrine Society's 97th annual meeting in San Diego, analysed the microbiota composition over one year in a group of men with varying blood glucose (sugar) and insulin levels.
The 116 men in the study were all African-American veterans participating in the D Vitamin Intervention in VA, or DIVA clinical trial, which the Department of Veterans Affairs funded, said the team.
Study subjects were divided into four groups based on changes in their glycemic, or blood sugar, control, as demonstrated by the oral glucose tolerance test (or the fasting glucose blood test in group 2), between the start and end of the one-year study.
The four glycemic control groups were (1) stable (unchanged) normal, (2) stable impaired, (3) worsened, and (4) improved. At the end of the study, the men gave stool samples for analysis of their gut microbiota.
The researchers found that men whose blood sugar control stayed normal over the year had more gut bacteria that are considered beneficial for metabolic health, whereas those who stayed pre-diabetic had fewer beneficial bacteria and more harmful bacteria.
In addition, the group whose glycemic control improved (group 4) had even more abundant Akkermansia – a strain of healthy bacteria - than the group that kept normal blood sugar control throughout the year.