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Metformin: What Does Your Gut Microbiome Have to Do with Blood Sugar?

POSTED ON IN Diet/Nutrition Latest News BY Chris Centeno

gut microbiome

Many type-2 diabetics and prediabetics take the common medication metformin to help control their blood-sugar levels. Discovered nearly a hundred years ago, metformin has been prescribed in the United States since 1995 and is currently billed as the most common oral medication for type-2 diabetes. While we know that metformin decreases the production of glucose in the liver, thereby controlling high blood sugar, its method of action, or how it accomplishes this, hasn’t been clear. Despite gastrointestinal upset (diarrhea, nausea, vomiting, etc.) being a side effect of metformin, a new study suggests that metformin may actually work by altering our gut microbiome, but if this is the case, can’t we just alter our gut microbiome without the drug?

What on Earth Is a Gut Microbiome?

Though it sounds like something straight out of a science-fiction novel set in outer space, our gut microbiome actually lives inside our intestines (though it can be found in other locations, such as the mouth and nose), and houses the majority of the immune system. At its basic level, our gut microbiome (aka gut flora) is our gut bacteria, but it does contain other organisms, such as yeasts and parasites.

While we might cringe at the thought of bacteria growing and thriving inside of us as we associate the word bacteria most commonly with infection, the truth is, the body couldn’t thrive without a healthy ratio of good-to-bad gut bacteria. And while we do want to try to keep the bad bacteria, such as E. coli for example, out of our gut microbiome, we want to work just as hard to keep the good bacteria, such as Lactobacillus, in. As you can probably understand, this is best accomplished via a healthy diet. The bad bacteria grow and thrive on unhealthy foods, while the good bacteria grow and thrive on healthy foods. When our bad bacteria overpower our good, this throws off our gut balance and is known as dysbiosis, so the more good bacteria we have, the better the chance we can fight off the bad bacteria when it enters our gut.

Probiotic supplements have been a hot topic in the past decade or so as they, along with a healthy diet, populate our gut with lots of good bacteria and help our gut microbiome flourish. Probiotics are especially crucial when taking antibiotics as antibiotics wipe out both the good and bad bacteria in the gut. Probiotics reseed the good so our gut, where, again, so much of our immune system lives, can be prepared to battle any bad bacteria that invades.  

The Power of the Gut Microbiome

When our gut microbiome isn’t happy, no part of the body’s happy. We’ve covered many topics over the years that demonstrate the power of our gut microbiome. Links to a few of these follow:

Study Shows Metformin Controls Blood Sugar via the Gut Microbiome

The new study set out to investigate how metformin controls blood glucose in type-2 diabetic patients. This was a randomized controlled trial in which subjects were placed into one of two groups: a placebo group or a metformin group. The study was double-blind, meaning neither the investigators nor the subjects knew which group they were in. After four months, results were measured and showed that the gut microbiome of the metformin group had been strongly affected, with an increase of good gut bacteria. The placebo group was then put on metformin for four months and had the same results as the first metformin group.

The study progressed further as researchers transferred microbiome samples from the metformin subjects into mice. The results? There was an improvement in the glucose tolerance in the mice, suggesting further that metformin works in type-2 diabetics by acting, at least in part, by improving the gut microbiome.

The upshot? According to this study, if you are taking metformin to keep your type-2 diabetes or prediabetes under control, the reason it works is because it may be giving your gut microbiome a boost. If the secret to metformin’s success lies in its ability to alter the gut bacteria, why not just alter the gut bacteria without the metformin? Why? There are no prescription medications without unintended side effects, and metformin, too, comes with a dose of adverse effects (e.g., loss of appetitie, abdominal pain, cramping, diarrhea, flatulence). Talk with your doctor; if you haven’t tried to get your blood sugar under control using a low glycemic natural diet with the addition of a high-quality probiotic to keep your gut microbiome happy, with their approval, it might be worth a try!


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    John Miller says

    How about the reverse.. Since we see the strong results of metformin in boosting good gut bacteria, and we also know the likelihood of changing what ppl eat is pretty low overall, do you see anything wrong with using metformin for other issues associated with unhealthy gut?


    Chris Centeno says

    Going to leave that one to people in that field.


    Barbara says

    Any suggestions on a good probiotic? Some seem to have a lot more strains than others.


    Chris Centeno says

    We currently take "Sedona Labs Iflora Multi-Probiotic Formula" available on Amazon. If based on this study something else seems better, we will let you know.


    Barbara says

    Thank you for the suggestion!!


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    About the Author

    Chris Centeno

    Christopher J. Centeno, M.D. is an international expert and specialist in regenerative medicine and the clinical use of mesenchymal stem cells in orthopedics. He is board certified in physical medicine as well as rehabilitation and in pain management through The American Board of Physical Medicine and Rehabilitation.…

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