Does Metformin counteract any positive effects of exercise on blood glucose levels?


manage diabetes effectively 300x237 Does Metformin counteract any positive effects of exercise on blood glucose levels?

I have been  one to preach that effective diabetes management constitutes a tripod of Diet, exercise and medications working harmoniously together. I still know this to be the truth but it seems Metformin might actually counteract any positive effects of exercise on blood glucose leves, this from a recent study by researchers at the university of Alberta.

(More on why diabetes research: is either Good science or bad medicine later)

It seems Researchers  at the University of Alberta, Studying the link between Exercise and Metformin the two most prescribed forms of  type 2 diabetes treatment discovered something curious.

In  a randomized, double-blind, crossover study – involving a multi-disciplinary team of researchers from five faculties at the U of A. They discovered that Combining Metformin and exercise was less effective in managing blood glucose control.

“The study had three objectives: we wanted to look at the effect of Metformin on exercise in people with type 2 diabetes, examine the effect of exercise on Metformin concentrations in the body, and finally to look at the effects of Metformin and exercise on glucose control, which is essential for people with diabetes,” says Dr. Normand Boulé Lead Researcher. 

Ten men and women between 30 and 65 with type 2 diabetes, but not taking glucose-lowering medication or insulin for their condition were recruited into the study. Participants were randomly assigned to take metformin or a placebo for the first 28 days of the study, then crossed over so those taking the placebo received metformin and vice versa for a second 28 day period. On days 27 and 28, participants spent six hours in the exercise physiology lab and performed different tests, including approximately 40 minutes of exercise on day 28.

“Metformin reduces glucose in the blood and many believe it does so by activating exercise-like pathways,” explains Dr.Boulé. “As expected, in our study metformin lowered the blood glucose concentrations measured during a two-hour period after lunch. But we found that on the non-exercise day metformin led to better glucose control after lunch than on the day our participants took metformin and exercised.”

Boulé thinks that because both metformin and exercise act to lower glucose levels, the combination may have triggered a counter regulatory response by the body to prevent glucose levels dipping too much.  “During exercise, glucagon concentrations increased in the blood (a hormone secreted by the pancreas that raises blood glucose levels) but when they combined exercise and metformin the glucagon levels were almost twice as elevated.” He also said that the combination of Metformin and exercise is not always worse than Metformin alone.

The findings of their study  was likely impacted by the timing of meals relative to the exercise session participants underwent and that the intensity of exercise may have had an impact as well, including the fact that these levels were measured after a single bout of exercise as opposed to regular daily exercise.

Before we anoint this research as gospel however we have to remember the parameters of it, its intent and the fact that there is now more questions than answers on this relationship in  Dr. Boule’s own words.

“What we’ve learned is that the relationship between exercise and metformin is complex, and this opens the door for more research to examine how different treatments work together, especially because exercise is widely prescribed for people with diabetes and metformin is often the first line drug of choice for treating type 2 diabetes.”

For once  this is a study that does not require  a control environment to mimic.

If you are a type 2 interested in knowing if Metformin is counteracting any positive effects on your exercise efforts then just do a small experiment and see how your body reacts to exercise with or without a Metformin dosage. Am by no means advocating that one goes without their Metformin for an extended period of time but a single dose experiment might help clarify if the Metformin and Exercise are working counter intuitively. The results might not jar a major shift in daily diabetes management routine but then again the knowledge might help tweak the diabetes management  routine.

update: Sept 02

Dan asked me  if the study used immediate or extended release Metformin? and after reaching out to Dr. Normand Boule, head Researcher of the study he confirmed that they used the Regular Release Metformin which made me wonder as well If the results would actually have  been different had they used Extended Release Instead. I suppose that’s fodder for the next study phase


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  1. This study seems to be pretty interesting, but i agree with you that a balanced approach of mangement, exercise, and eating right really can’t go wrong. Do you know if the study used immediate or extended release metformin?

  2. Very interesting stuff. Thank you!

    I’ve been very interested in whether my metformin is doing me more harm or good (I’m on MDI so my main concern at this point is not whether metformin is lowering my blood sugar — it isn’t. That’s why I went on insulin. The reason I stay on metformin is a belief that it is helping my insulin resistance and a fear that if I went off the metformin, I would need much more insulin. But I have no idea whether that’s true or not. I may just be on metformin because that’s what my doctor puts type 2 diabetics on, whether it’s helping them or not.)

    The harm aspect is because metformin depletes certain nutrients. The big one is B12. I believe that everyone on metformin should get their B12 levels tested once a year! I supplement B12 and I get my levels tested every December. This is really important because one of the symptoms of B12 depletion is neuropathy and if a diabetic gets neuropathy, everyone will just be sad that they’re dealing with diabetic complications. It almost never occurs to anyone that they might be experiencing neuropathy because the metformin depleted their B12. It’s even more masked because it takes about 5 years for B12 to get depleted to a level where there will be symptoms and diabetes complications tend to become most prevalent about 5 years after diagnosis. So it all lines up and makes the B12 depletion invisible.

    But B12 is a big deal and going depleted for too long can put a person permanently in a wheelchair. So . . . all you diabetics who take metforin and are reading this: ask your doctor to test your B12 levels!!!

    • thanks as usual for the insight Sparrow. Yes B12 deficiency is one of those diabetes complications that is not considered dangerous enough to get much attention. I am actually researching this for a future post on those diabetes complications that get ignored or given little thought and I am sure to include this.,

    • Thanks guys, I just about lost it looking for this.

  3. Nice blog Ronnie. Given that Metformin reduces glucose in the blood by activating exercise-like pathways then, given a choice, exercise would be my preference for blood sugar management over medication.

    Exercise may also lead to lower body fat percentage which helps with intramyocelular lipids and, hopefully, any extra muscle fibre also helps reduce overall blood sugar levels.

    I’ve been looking for quality research, like the material that you’ve posted here, that shows measured relationship between body fat percentage and blood sugar levels.

  4. My hat is off to your astute command over this topic-bravo!

  5. I really needed to find this info, thank God!


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