Common diabetes drug may work by changing gut bacteria, study finds

A group of diabetics taking metformin had drastic changes in their gut flora
The drug speeds growth of two types of bacteria which help control blood sugar
A probiotic diet may be beneficial for people with diabetes, say researchers
Specifically akkermansia and bifidobacterium strains are recommended

The most common medication for type 2 diabetes may work by changing the composition of the bacteria in the gut, a study reveals.

Researchers discovered that certain strains of bacteria – which can reduce blood sugar levels – grew faster in the presence of the drug metformin.

Controlling blood glucose levels is crucial for people with diabetes to avoid serious health complications, such as kidney disease and vision loss.

The new findings add to the ever-growing body of scientific research focusing on the crucial role our gut flora plays in our overall health.

And the researchers suggest following a probiotic diet may be beneficial for people living with diabetes – which affects 28 million Americans and 3.6 million Britons.

‘Recent evidence implicates the gut microbiota as a site of metformin action,’ the researchers wrote in the journal Nature Medicine.

Strains of bacteria called akkermansia and bifidobacterium help control blood sugar

‘In a double-blind study, we showed that metformin had strong effects on the gut microbiome.’

Metformin is believed to lower blood sugar levels primarily by reducing the amount of glucose produced and released by the liver.

Yet slow-release versions of the drug appears to be just as effective – even though only small amounts of it ever reach the liver.

This caused researchers to suspect there was more to the story.

As the trillions of microbes that live in the intestines have been known to influence drug metabolism – the process by which the body breaks down and converts medication into active chemical substances – they set about to investigate if this was the missing piece of the puzzle.

MICROBIOME: DOES IT CONTROL EVERYTHING?

Researchers now estimate that a typical human body is made up of about 30 trillion human cells and 39 trillion bacteria.

These are key in harvesting energy from our food, regulating our immune function, and keeping the lining of our gut healthy.

Interest in, and knowledge about, the microbiota has recently exploded as we now recognise just how essential they are to our health.

A healthy, balanced microbiome helps us break down foods, protects us from infection, trains our immune system and manufactures vitamins, such as K and B12.

It also sends signals to our brain that can affect mood, anxiety and appetite.

Imbalances in the gut are increasingly being linked to a range of conditions. Last year, scientists at California Institute of Technology found the first ever link between the gut and Parkinson’s symptoms.

The composition of our gut microbiota is partly determined by our genes but can also be influenced by lifestyle factors such as our diet, alcohol intake and exercise, as well as medications.

The team, from the University of Gothenburg, Sweden, and the University of Girona, Spain, recruited 40 volunteers who were newly diagnosed with type 2 diabetes.

For four months, one group was assigned to take metformin and another was given a placebo – and all followed a low-calorie diet.

It was discovered that those taking the drug had drastic changes in their gut flora.

In particular, this group showed a growth of strains of bacteria in their intestines called akkermansia and bifidobacterium.

Lab experiments revealed that both types also grew faster in the presence of metformin.

Next, the scientists induced type 2 diabetes in mice by giving them a high fat diet. Some were fed the faeces of the individuals on metformin to pass on the beneficial bacteria.

The mice given this saw an improvement in their glucose tolerance – a measure of how well animals can control blood sugar levels.

But the mice who were given faeces taken from people before their treatment – hence without the two strains of bacteria – had no such effect.

Together, the findings of these studies suggest that metformin at least partly works by encouraging the growth of gut bacteria such as akkermansia.

However, the researchers admitted that they still do not understand exactly how the bacteria might be doing this.

But they believe that some people with diabetes might see similar benefits by making dietary changes to encourage the growth of akkermansia and bifidobacterium.