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Gut bacteria may play a role in diabetes

Summary: People with higher levels of Coprococcus gut bacteria tend to have greater insulin sensitivity, while those with higher levels of Flavonifrator have lower levels of insulin sensitivity. Researchers say that specific gut bacteria may play a significant role in the development of type 2 diabetes.

Source: Cedars Sinai Medical Center

One type of bacteria found in the gut may contribute to the development of type 2 diabetes, while another may protect against the disease, according to the first results of an ongoing prospective study led by Cedars-Sinai researchers.

The study, published in the peer-reviewed journal Diabetesfound that people with higher levels of a bacteria called Coprococcus tended to have greater insulin sensitivity, while those whose microbiomes had higher levels of the Flavonifractor bacteria tended to have lower insulin sensitivity.

For years, researchers have sought to understand why people develop diabetes by studying the composition of the microbiome, which is a collection of microorganisms that includes fungi, bacteria and viruses that live in the digestive tract.

The microbiome is believed to be affected by medications and diet. Studies have also found that people who don’t process insulin properly have lower levels of a certain type of bacteria that make a type of fatty acid called butyrate.

Mark Goodarzi, MD, Ph.D., director of the Endocrine Genetics Laboratory at Cedars-Sinai, is leading an ongoing study that follows and observes people at risk for diabetes to see whether those with lower levels of these bacteria develop the disease.

“The big question we hope to address is: did microbiome differences cause diabetes, or did diabetes cause microbiome differences?” said Goodarzi, who is the study’s senior author and principal investigator of the multicenter Microbiome and Insulin Longitudinal Evaluation Study (MILES).

The investigators involved in MILES have been collecting information from participating white black and non-Hispanic adults between the ages of 40 and 80 years since 2018. A previous cohort study from the MILES study found that cesarean delivery is associated with an increased risk of developing pre-diabetes and diabetes.

For the latest study in this ongoing study, investigators analyzed data from 352 people without known diabetes who were recruited from the Wake Forest Baptist Health System in Winston-Salem, North Carolina.

Study participants were invited to attend three clinic visits and collect stool samples prior to the visits. The investigators analyzed the data collected on the first visit. They conducted genetic sequencing on the stool samples, for example, to study participants’ microbiomes and look specifically for bacteria that previous studies have found to be associated with insulin resistance.

Each participant also completed a diet questionnaire and took an oral glucose tolerance test, which was used to determine ability to process glucose.

The investigators found that 28 people had oral glucose tolerance results that met criteria for diabetes. They also found that 135 people had prediabetes, a condition in which a person’s blood sugar levels are higher than normal but not high enough to meet the definition of diabetes.

The research team looked at associations between 36 butyrate-producing bacteria found in stool samples and a person’s ability to maintain normal insulin levels. They controlled for factors that could also contribute to a person’s risk of diabetes, such as age, gender, body mass index and race. Coprococcus and related bacteria formed a network of bacteria with beneficial effects on insulin sensitivity.

Despite being a butyrate producer, Flavonifrator has been associated with insulin resistance; Previous work by others has found higher levels of Flavonifrator in the stool of people with diabetes.

This shows a diagram of the intestines
The microbiome is believed to be affected by medications and diet. The image is in the public domain

Investigators continue to study samples from patients who participated in this study to learn how insulin production and microbiome composition change over time. They also plan to study how diet can affect the bacterial balance of the microbiome.

Goodarzi emphasized, however, that it’s too early to know how people might change their microbiome to reduce their risk of diabetes.

“As far as the idea of ​​taking probiotics is concerned, that would actually be quite experimental,” said Goodarzi, who is also the Eris M. Field Chair in Diabetes Research at Cedars-Sinai.

“We need more research to identify the specific bacteria we need to modulate to prevent or treat diabetes, but it’s coming, likely in the next five to 10 years.”

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About this microbiome and diabetes research news

Author: Press office
Source: Cedars Sinai Medical Center
Contact: Press Office – Cedars Sinai Medical Center
Image: The image is in the public domain

Original search: Free access.
“Butyrate-Producing Bacteria and Insulin Homeostasis: The Microbiome and Insulin Longitudinal Assessment Study (MILES)” by Jinrui Cui et al. Diabetes


Butyrate-Producing Bacteria and Insulin Homeostasis: The Microbiome and the Longitudinal Insulin Assessment Study (MILES)

Gut microbiome studies have documented the depletion of butyrate-producing taxa in type 2 diabetes. We analyzed associations between butyrate-producing taxa and detailed measures of insulin homeostasis, the dysfunction of which underlies diabetes in 224 non-Hispanic whites and 129 African Americans, all of whom completed an oral glucose tolerance test. The fecal microbiome was assessed by shotgun sequencing of the entire metagenome with taxonomic profiles.

We examined associations between 36 butyrate-producing taxa (n = 7 genera and 29 species) and insulin sensitivity, insulin secretion, disposition index, insulin clearance, and prevalence of dysglycemia (pre-diabetes plus diabetes, 46% of cohort), adjusting for age, sex, BMI, and race.

the gender Coprococcus was associated with greater insulin sensitivity (β = 0.14; P = 0.002) and willingness 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).

In contrast, Flavonifrator was associated with lower insulin sensitivity (β = −0.13; P = 0.004) and willingness index (β = −0.11; P = 0.04) and higher prevalence of dysglycemia (OR 1.22; 95% CI 1.08–1.38; P = 0.0013). Species-level analyzes found 10 bacteria associated with beneficial directions of effects and two bacteria with adverse associations in insulin homeostasis and dysglycemia.

While the majority of butyrate producers analyzed appear to be metabolically beneficial, this is not the case for all of these bacteria, suggesting that therapeutic measures targeting the microbiome to prevent or treat diabetes should be targeted at specific butyrate-producing taxa, and no to all butyrate producers.