Gut bacteria may play a role in diabetes

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

Source: Sinai Cedars 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 early results from an ongoing prospective study by Cedars-Sinai researchers.

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

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

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

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

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

Investigators involved in MILES have been collecting information from participating black and white non-Hispanic adults between the ages of 40 and 80 since 2018. A previous cohort study of the MILES trial found that cesarean delivery is associated with a risk higher to develop prediabetes. and diabetes.

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

Study participants were asked to attend three clinic visits and to collect stool samples before the visits. The investigators analyzed the data collected during the first visit. They performed genetic sequencing on stool samples, for example, to study participants’ microbiomes and specifically look 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 their ability to process glucose.

Investigators found that 28 people had oral glucose tolerance results that met the 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 analyzed 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 might 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.

Although a butyrate producer, Flavonifractor was associated with insulin resistance; previous work by others found higher levels of Flavonifractor in the stools of people with diabetes.

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

Researchers are continuing 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 pointed out, however, that it’s too early to know how people can change their microbiome to reduce their risk of diabetes.

“As far as the idea of ​​taking probiotics, that would really be somewhat experimental,” said Goodarzi, who also holds 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 happening, probably within the next five to 10 years.”

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About this microbiome and diabetes research news

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

Original research: Free access.
“Butyrate-producing bacteria and insulin homeostasis: the Longitudinal Microbiome and Insulin Assessment Study (MILES)” by Jinrui Cui et al. Diabetes


Abstract

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

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

We examined associations between 36 butyrate-producing taxa (not = 7 genera and 29 species) and insulin sensitivity, insulin secretion, disposition index, insulin clearance and prevalence of dysglycemia (prediabetes plus diabetes, 46% of the cohort) , adjusting for age, sex, BMI and race.

Genre Coprocococcus was associated with greater insulin sensitivity (β = 0.14; P = 0.002) and disposition index (β = 0.12; P = 0.012) and a lower rate of dysglycaemia (odds ratio [OR] 0.91; 95% CI 0.85–0.97; P = 0.0025).

On the other hand, Flavonifractor was associated with lower insulin sensitivity (β = −0.13; P = 0.004) and disposition index (β = −0.11; P = 0.04) and a higher prevalence of dysglycaemia (OR 1.22; 95% CI 1.08-1.38; P = 0.0013). Species-level analyzes found 10 bacteria associated with directions of beneficial effects and two bacteria with detrimental associations on insulin homeostasis and dysglycemia.

Although most of the butyrate producers analyzed appear to be metabolically beneficial, not all of these bacteria are, suggesting that microbiome-directed therapeutic measures to prevent or treat diabetes should be targeted at specific taxa. butyrate producers rather than all butyrate producers.

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