JUN 02, 2017 09:31 AM PDT

Gut microbes and metformin team up

WRITTEN BY: Kerry Evans

Metformin is a drug that helps people with type 2 diabetes control their blood glucose level, but nobody really knows how it works.

 

There is evidence that metformin suppresses the hepatic output of glucose by altering the activity of AMPK-dependent and independent signaling pathways. However, some studies suggest that its glucose-lowering activity occurs in the bowel, and researchers at Sahlgrenska Academy knew that the microbiome is altered in people with diabetes.

 

Metformin alters the gut microbiome.

 

To determine how the microbiome is affected by metformin, they sequenced the microbiomes of 22 people with newly diagnosed diabetes - before and after they started taking metformin or a placebo. They also transferred human fecal samples to mice and studied the effects of these microbes on glucose metabolism.

 

First, the group performed whole-genome shotgun sequencing on fecal samples to characterize the microbiome. The abundance of only one type of bacteria changed in the placebo group, but metformin significantly altered the abundance of 86 strains after 4 months of treatment. The majority of these belonged to the γ-proteobacteria and Firmicutes. Specifically, metformin altered the abundance of Escherichia and Intestinibacter species.

 

Next, they investigated whether the metformin-altered microbiota had any effect on blood glucose. To do this, they transferred fecal samples from humans to germ-free mice and measured glucose tolerance. Mice that received fecal samples from people treated with metformin for 4 months (versus untreated) improved their glucose tolerance.

 

Not only did metformin alter the abundance of some groups of bacteria, it also altered bacterial gene expression. For example, metformin treatment increased the expression of genes for bacterial secretion systems, two-component systems, ATP-binding cassette transporters, chemotaxis, antimicrobial peptide resistance, LPS biosynthesis, and certain metabolic pathways.

 

Gut bacteria are known to produce short-chain fatty acids (SCFAs) and regulate bile acid metabolism. It’s possible that these activities could work with metformin to benefit the host. Male subjects who were treated with metformin for four months had higher concentrations of fecal propionate and butyrate (SCFAs). Metformin also increased the fecal concentrations of organic acids such as lactate and succinate. As for bile acids, metformin did not alter bile acid metabolism in the gut, but plasma bile acid concentrations did increase.

 

According to study author Fredrik Bäckhed, “imagine if we can change the intestinal flora in the future so that more people respond to treatment, and that adverse events can be reduced by changing the gut microbiota of patients who will take metformin.”

 

Sources: Nature Medicine, Science Daily

 

 
About the Author
  • Kerry received a doctorate in microbiology from the University of Arkansas for Medical Sciences.
You May Also Like
NOV 20, 2019
Cardiology
NOV 20, 2019
Stem Cells Improve Post Infarction Repair
Following a heart attack, tissues within the heart are often damaged. Once damaged, the heart is incapable of regeneration of these tissues. These dead are...
NOV 20, 2019
Cell & Molecular Biology
NOV 20, 2019
Why TB and HIV Occur Together So Often
Tuberculosis (TB) is among the world’s leading causes of death, and is the primary cause of death in people who are HIV-positive....
NOV 20, 2019
Cell & Molecular Biology
NOV 20, 2019
RNA Polymerases Can Signal to One Another Over Long Genomic Distances
Scientists have taken a close look at transcription in the Escherichia coli bacterium at the level of a single molecule....
NOV 20, 2019
Cell & Molecular Biology
NOV 20, 2019
Researchers Discover a Cause of Antibiotic Resistance
For years, people have relied on antibiotics to cure bacterial infections, and many of those antibiotics are now becoming less effective....
NOV 20, 2019
Microbiology
NOV 20, 2019
Raw and Cooked Foods Have Different Effects on the Microbiome
The gut microbes we carry are impacted by many factors, including our diet....
NOV 20, 2019
Microbiology
NOV 20, 2019
How Penicillin Blows Up Bacteria
Scientists have finally revealed more about why pathogenic microbes burst when they encounter the antibiotic....
Loading Comments...