Different types of gut microbiome may contribute to or protect against type 2 diabetes

There is significant interests in the role of gut microbiome on the risks of developing insulin resistance and type 2 diabetes. These microbiome is thought to be affected by medications and diet. Specifically, previous studies have shown that type 2 diabetes was associated with having lower levels of a certain type of bacteria that produce a type of fatty acid called butyrate. A prospective study led by investigators at Cedars-Sinai analysed associations between butyrate-producing taxa and detailed measures of insulin homeostasis, whose dysfunction underlies diabetes in 224 non-Hispanic Whites and 129 African Americans. Study participants were asked to attend three clinic visits and collect stool samples prior to the visits. They conducted genetic sequencing on the stool samples, for example, to study the participants' microbiomes, and specifically look for bacteria that previous studies have found to be associated with insulin resistance. Each participant also filled out a diet questionnaire and took an oral glucose tolerance test. The research team analyzed associations between 36 butyrate-producing bacteria found in the stool samples and a person's ability to maintain normal levels of insulin. They controlled for factors that could also contribute to a person's diabetes risk, such as age, sex, body mass index and race. The study, published in the peer-reviewed journal Diabetes, found people with higher levels of a bacterium called Coprococcus tended to have higher insulin sensitivity (β = 0.14; P = 0.002) and disposition index (β = 0.12; P = 0.012) and a lower rate of dysglycemia (odds ratio [OR] 0.91; 95% CI 0.85–0.97; P = 0.0025). Conversely, Flavonifractor was associated with lower insulin sensitivity (β = −0.13; P = 0.004) and disposition index (β = −0.11; P = 0.04) and higher prevalence of dysglycemia (OR 1.22; 95% CI 1.08–1.38; P = 0.0013). The study showed that although most butyrate producers analyzed appear to be metabolically beneficial, this is not the case for all such bacteria. Future therapeutic strategies to target, microbiome to prevent or treat diabetes should therefore targeted to specific butyrate-producing taxa rather than all butyrate producers.