Metformin reduces heart disease risk in Type 1s:

It apparently improves heart disease markers and NOT because it’s lowering BGs; it has a completely different mechanism involving microRNAs that suppress new blood vessel growth:

I love studies like these which show ways to improve health markers in T1s that do NOT rely solely on BG lowering.


Fascinating, @TiaG! I have read quite a few studies on metformin and Type 2s, but this looks really interesting for Type 1s too in terms of understnading why/ how it works:

metformin treatment successfully reduced the levels of microRNAs.

Moreover, as the levels lowered, there was a corresponding decrease in the amount of circulating endothelial cells, which indicates an improvement in vascular repair.

“These results confirm that as well as improving a patient’s blood sugar control, metformin is working to protect the heart,” explains Dr. Weaver.

Do we know of any downside to taking metformin? Is this something that our kids could take?

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Gas ?

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well my dad is not supposed to take it because he has had kidney failure issues in the past and is on diuretics that also worsen kidney issues. It can exacerbate those. So it’s contraindicated for him. HE also has a plethora of health issues.
I think it can also deplete B12 stores or reduce absorption or something?

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Diarrhea is fairly common, from what I’ve heard.

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It could be detrimental for endurance based sports. You are reducing the liver’s ability to contribute fuel. And it can also impact the absorption of carbs that are consumed prior to an event.

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@Eric, can you explain the how/ why?

Smells and tastes like rotting fish to me…ugh! And I experienced a lot of exercise lows (though I was on MDIs then and knew nothing about basal adjustments).


I personally have been taking metformin for years and haven’t had any problems. I had stomach issues since before starting and metformin hasn’t had any impact in that regard that I can tell.

I did recently test as being quite deficient in vitamin B12, so that’s concerning. But I’m on PPIs in addition to metformin, and I am low or low-normal in virtually all vitamins and minerals that were tested. These tests have all been fine for years up until now, so it’s hard to tell if it’s this combination of medications or something else causing it.

Metformin does help me to take a bit less basal insulin and erases my dawn phenomenon. There is definitely a very noticeable impact on my BG when I forget a dose. Metformin has also allowed me to lose weight for the first time in years, though it doesn’t prevent weight gain. So all around positive experience in addition to what I keep hearing about its positive impact on possibly helping to prevent heart disease and cancer.


Metformin reduces the amount of liver glycgoen that is released. Liver glycogen is a fuel source, so reducing a fuel source would be a negative impact in an endurance activity.

In addition, metformin also slows the absorption of glucose in the intestines. This could have a negative impact by reducing the ability for exogenous carbs to provide immediate fuel for an activity.


There is a lot of metformin info here:

One of the big reasons I take it is for my heart. But there are a lot of other reasons.


For the most typical person on Metformin, are they more likely to have their liver releasing excessive amounts of glycogen? Or is it so different from one person to another that it is hard to draw comparisons?

It would certainly vary from one person to the next. The “typical person on Metformin” is a Type 2. It is the most widely prescribed drug for T2, and generally the first thing that is tried for T2’s. (It is used by T1’s too of course, but obviously prescribed much more for T2’s.)

T2’s do produce more glucose, and also have more glucose circulating in their blood from that over production than non-D’s. T2’s can often have glycogen cycling, which is where glycogen is simultaneously created and broken back down into glucose.

Metformin changes a lot of different things. It reduces glucose production, it reduces glycogen cycling, and it reduces gluconeogenesis (which is the generation of glucose from non-carbohydrate sources). It also changes the amount of cortisol that is available in the body.

In answer to your question:

Yes, the amount of glucose produced by T2’s is generally higher than it is in non-D’s. It varies of course, but it can be about twice as high in T2’s.

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There are many T1D’s who are diagnosed with IR (Insulin Resistance). I was diagnosed with IR in 1998. That was 53 years after my diabetes diagnosis. There are/were four of my relatives with T2, so I guess I inherited a gene that led me to IR. I did gain weight in the 1990s and that was the trigger that produced the IR. I used a daily dosage of 2000 mg of Metformin for 8 years, and I gradually lost all of the weight I had gained. I have stopped the Metformin. My IR and my T1D are under good control now.


@Richard157, I was really impressed by your results. I had no idea that Metformin could be so powerful for T1s.

What is your thought on T1D kids using Metformin for prevention?

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Michel, I do not know if Met affects everyone the same way. It reduced my appetite, and I did not eat as much. I have T1 and T2 friends who did not lose so much weight while using Met. Since I was not eating as much, I used less insulin. Lower insulin dosages certainly helps with losing weight.
I have no opinion on kids using Met. That is a new topic for me. Loose bowels in the beginning weeks would certainly be an aggravation. It took me about three weeks to get used to that.

I’m new here and mot sure if this thread is active but thought I would do a quick comment from own experience. I’ve been on Metformin about 9 months in effort to help my heart disease. I can’t tolerate statins. My worry with children would be the lows. I’ve experienced more low BS since starting than ever before. I’m on a pump with CGM but lately that doesn’t alarm as quickly as I drop when I’m active. And now I’m not physically as aware when dropping. Last week I dropped to 35 when out camping. Very scary. A child would be in trouble. I hope this helps.


Thanks very much, @Pamela!

What is the rest of your experience with Metformin? Do you see benefits?

Welcome Pamela :slight_smile:

I used Metformin XR with a long-acting insulin, and I found that I needed to drop my daily basal rate by 1 unit. I started taking Metformin XR in the mornings because that’s what my doctor recommended, but Metformin XR peaked a few hours after taking it, and I needed that peak to occur around 10 pm - 12 am. So I switched to the evening. When I was taking Metformin XR in the mornings, I also had trouble with lows during the day, and if I lowered my basal to the point where I wasn’t having lows, I had trouble with highs at night!

Switching to the evening solved both those problems, but I still ended up needing 1 unit less basal per day.

I’m currently taking a break from Metformin because I switched from Tresiba to Lantus, and I wanted to see how things were going on Lantus without Metformin. I’m still evaluating; I may start taking Metformin again. I’m not sure yet.

Short-acting insulin in a pump already responds more to activity than long-acting insulin does, so I could see why activity and exercise became problematic for you. It may be worth trying out taking your dose at night?

How many mg/day were you taking? Was it the extended release (XR) version?

I’m also curious/interested. Have you seen any benefits on your heart?

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