JUN 02, 2017 9:31 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
MAR 27, 2020
Chemistry & Physics
MAR 27, 2020
Hand Sanitizer Shorage: Liquor, Perfume, and Medication Producers Joined the Race to Restock the Shelves
Amid the coronavirus pandemic, the habit of thorough and frequent handwashing are among the best defense against the con ...
APR 20, 2020
APR 20, 2020
A Neuropsychiatric Crisis Might Follow COVID-19
Past pandemics have been accompanied by a rise in a variety of mental health and neurological problems.
APR 27, 2020
APR 27, 2020
CDC Adds to the List of COVID-19 Symptoms
The pandemic virus that causes COVID-19 has now infected nearly 3 million people, and killed over 200,000.
MAY 07, 2020
Clinical & Molecular DX
MAY 07, 2020
An 8 Minute DNA Test For Salmonella
Australian researchers have created a sensitive, super-fast test for five different serotypes of Salmonella which could ...
MAY 15, 2020
MAY 15, 2020
Support the Microbiome So the Immune System Can Do Its Job
Research has long connected the human microbiome and immune system function, and now a recent study pinpoints a key poin ...
MAY 17, 2020
MAY 17, 2020
Substantial Antiviral Response Seen in Adults Recovered from COVID-19
Some good news comes as researchers scramble for potential vaccine candidates amidst the global COVID-19 pandemic. Scien ...
Loading Comments...