Metformin and Type 1 Diabetes – An Experiment


Metformin is not usually prescribed for Type 1 diabetes, but over the past couple years, inspired in part by Mike’s experience on it (see here, here, here and here), I’ve become interested in trying it. Not only has it been in widespread use as a treatment for Type 2 diabetes since its approval in 1994, but it’s currently being investigated for potential cognitive and anti-cancer benefits as well. As Mike has asked, “Could metformin be the new aspirin?” 

The typical explanation for why metformin is not prescribed to people with Type 1 diabetes is that metformin increases your insulin sensitivity — and given that, by definition, people with Type 1 don’t make any insulin, it won’t help them. But I see two obvious holes in that logic. First, people with Type 1 diabetes do have insulin in their bodies; it’s just administered in a different way (i.e. injected subcutaneously, rather than secreted by the pancreas). And as anyone who’s struggled with the dawn phenomenon knows, people with Type 1 diabetes experience insulin resistance, too.

And second, metformin does more than just affect insulin sensitivity. It also appears to regulate the genes responsible for causing the liver to release glucose into your blood. As you may know, your pancreas and your liver work closely together to maintain a proper level of glucose in the blood. When you’ve got a lot of glucose in your blood, your pancreas secretes insulin to remove it (provided you don’t have Type 1 diabetes!). And when you don’t have sufficient external glucose – like when you’re sleeping — your liver releases some stored glucose so that your blood sugar does not drop too low. To put this a different way, insulin is what keeps a non-diabetic person’s blood glucose from getting too high; the liver (by releasing glucose stores when appropriate, triggered by the hormone glucagon) is what keeps a non-diabetic person’s blood sugar from going too low. 

I feel like I have an extremely overactive liver, which seems to take any excuse it can get to dump additional sugar into my blood stream, whether it’s needed or not. And I also seem to have difficulty absorbing the insulin delivered by my pump. So I was really excited when my doctor allowed me to start trying metformin a couple weeks ago.

When I picked up my first prescription, I decided to ask the pharmacist for some advice — namely, what sort of side effects I should watch out for, given that I’d read stories online about uncontrollable vomiting. But no, she said, in front of the group of people waiting behind me in line. The most frequent side effect is diarrhea.  That’s why they start you on a low dose. 

With that noted (both by me and my fellow shoppers), I went home and took a pill with dinner, and gave myself a bit less insulin than I’d normally take (since metformin increases insulin sensitivity it also comes with an increased risk of hypoglycemia for people taking artificial insulin — i.e. Type 1s; see below). Then I waited to see what would happen.

I’m happy to say that in terms of my pharmacist’s warnings I was lucky: no GI upset. And I’m even happier to say that starting with the very first dose, I began to notice a difference in my post-meal blood sugars. Not only did my blood sugar start to rise more slowly than normal after eating (which itself is fascinating — I’d always thought I absorbed food very quickly, but perhaps what’s really going on is that my liver is dumping glucose into my blood right after I eat), but the post-meal line on my Dexcom was much smoother than normal. 

I can’t remember what I ate for dinner the first two nights, but I can tell you this: my total daily insulin dropped from about 22 to 25 units per day to between 15 and 20. Considering that about 10 of those units are basal, that’s a really big reduction — in the most extreme case, we’re talking 5 units of bolus insulin per day. (Granted, I eat a very low-carb diet, but still.) I felt an eerie sense of ease — as if the metformin were somehow making my diabetes . . . dare I say it . . . simpler, and easier to control. It was an amazing feeling. 

That was about two weeks ago, and I’m now up to a full 1000 mg daily dose (in my case broken into twice daily 500 mg tablets). My past 5 days’ worth of totals (including basal insulin) are: 18.35u, 14.65u, 15.975u, 17u and 21.8u and my blood glucose hasn’t spiked above 200 mg/dl. (Again, I eat an extremely low-carb diet, am on a Dexcom CGM in addition to a pump, and am a wee bit obsessive — but even with all that, this is unusual for me.) When it comes to my own diabetes management, I am a Metformin believer. 

With that said, a major caveat: in addition to whatever it’s doing with my liver, the metformin also definitely increases my insulin sensitivity. I have had more lows these past two weeks than normal (which I figure is to be expected as I learn how to use it), and I have had to drop not just my mealtime boluses, but some of my basals as well. I do not recommend trying any of this without direct supervision or help from your diabetes doctor or endocrinologist, since the risk of hypoglycemia increases for people with Type 1 (it’s not a problem for people who are not on artificial insulin, which is why hypoglycemia is not typically an issue with metformin and non-insulin-taking Type 2s). In other words: this is not medical advice!

But with that said, I’m personally pretty excited. Stay tuned for further updates. And if you’ve had experience yourself with Metformin and Type 1, I’d love to hear about it in the comments section. 

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17 Comments on "Metformin and Type 1 Diabetes – An Experiment"

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Hiya, my doc decided to double my metformin dose a couple of weeks ago and I’ve been waking up with blood sugars around 4-5mmol instead of the normal 6-7mmol and no more post coffee and breakfast spikes. I low carb too and I think I’m going to have to do a basal test and readjust my levermir now and novorapid ratios. I have noticed (this maybe tmi) that I go to the loo a lot easier lol so not needing my daily hit of linseeds as much. I have pcos and my hair regrowth has got a lot better, less… Read more »
I am 30 years old and live in Nigeria. I was diagnosed with type 1 diabetes, July 2014 and since then I have had to change my lifestyle – diet, alcohol intake and use of marijuana. it has been no easy feat but I am getting used to it now. Earlier after my diagnosis, I was placed on a strict diet and medication of daily regular glucose checks and insulin injection after breakfast and after dinner. Unfortunately, the insulin doses cause me severe occasions of blurry vision which lasted for days; until my father and doctor who happens to also… Read more »

I find it very usefull info about metformin and Type 1 Diabetes ,my grandmother is diabetic thanks a lot.

My daughter is a type 1 and was exhibiting what the doctor termed, “leaky liver.” Because her liver was so active in releasing glucagon, it became impossible to lower her glucose levels. She was taking enormous amounts of insulin to counter the debilitating highs, and we still ended up in the pediatric intensive care unit for treatment of DKA. After four months of dealing with these highs, I implored the endo to prescribe Metformin. He was very resistant, but he finally relented because of my daughter’s misery, and her dangerous glucose levels. A week after starting Metformin, my daughter stabilized… Read more »
Dominik, I feel your pain with the heart palpitation thing. I am a type 1 diabetic, and I used to get horrendous high blood pressure. My explanation for myself may help you; it will sound very weird, but it works for me (your results may vary). Insulin lowers plasma cholesterol levels, and metformin intensifies this effect. “Hurray” say some people. But I’ve learned that the brain depends on cholesterol, and so does lower blood pressure. I had senior moments and high blood pressure until I stopped eating almost all sources of digestible carbohydrate, and used saturated fat instead as my… Read more »
Do you guys use generic metformin or brand name Glucophage? In his book, The Diabetes Solution, Dr. Bernstein mentions that in his experience some people experience more side effects on generic metformin compared to its brand name counterpart, Glucophage. I actually tried generic metformin (been type 1 for approximately 22 years now) about a year ago for about two weeks or so but it gave me heart palpitations (typically I noticed them as I lay in bed right before going to sleep). This worried me a bit. At the time I was already having difficulty sleeping through the night (I… Read more »

Ellen, I personally have not had this issue. My understanding is that people with Type 1 often have messed up counter-regulatory mechanisms to begin with. I would recommend speaking about this with your doctor. (And if I do more research on this myself I will try to remember to ask this question!)

Thanks so much for sharing your experience. I was ‘raised’ in a very traditional type 1 way, and the idea of taking type 2 drugs seemed completely crazy when my new diabetes dr suggested it to me. No one had ever even mentioned to me that this might be an option! So after looking for what little info is out there, I’ve decided to give it a go and see what happens, but stories like yours are quite motivating. Will be interesting to see how you get on with it – I will be looking to start in October. Thanks again… Read more »

Do you worry about the counter-regulatory mechanism with respect to hypoglycemia while on metformin – I’m concerned about a person having an undetected low, and the metformin inhibiting the liver from releasing glycogen in response.


People taking metformin should be aware that B12 is one of the vitamins this drug depletes.
Please either just supplement with methylcobalamin sublingual or have your doctor test for B12 levels.
B12 is VERY hard to overdose on, so do some research and make your own decision.
Dr. Hyla Cass has a book on Amazon called “Supplement Your Prescription” that lists several drugs and the various vitamins and minerals they deplete. It is a highly useful book since there ARE so many drugs in that category.

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