Type 1s on Metformin and Pump

Hi Everyone,

My endo recently suggested Metformin for a bit to lower my insulin resistance. I’m currently on a Tandem pump and wanted to see if anyone has any opinions or experience being on both.


I was put on Metformin last August and have been on a pump since 1992, and it made a big difference in my overall control.
Some people have stomach issues with Metformin, and I noticed I get a bit gassier with green veggies than I did before starting it, but the pros definitely outweigh the cons for me.
You won’t know if you don’t try.

I’ve been prescribed it for nearly 2 years, and I’ve been off and on because I get some pretty serious GI issues while on it. But oh yeah, it works really well when I’m on it.

I decided to start it. It has definitely helped me so far. I think I still need to adjust my numbers a bit but so far so good. I have had mild stomach issues and hopefully they go away soon. Thanks for the advice!

Thanks for the response! Thankfully my GI issues have been mild. The first few days were tough but they are getting better.

Hello Marcela, I was diagnosed with diabetes in 1945, when I was 6. When I stopped using animal insulin and started synthetic insulin in the mid 1990s, I gained weight. That triggered my insulin resistance (IR) in 1998. I do not have any T1 relatives, but I do have four T2 relatives. I probably inherited the T2 gene, and that caused my IR. I am T1 with a T2 characteristic, but that does not make me T2. I used Metformin, 2000 mg per day to help with the IR. The extended release form of Metformin (Metformin ER) did not cause much of a gastric problem. The Metformin caused me to have less appetite. I ate less, and used less insulin (Humalog) in my pump. I exercised a lot. I lost all the weight I had gained. Now I am using only 1000 mg of Metformin, one pill per day.
Metformin has helped me very much!
Good luck to you while using Metformin!

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I’m one year post dx and was told that type 1s cannot use Metformin? That is not correct?

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hi @TiJoy, we can’t give you medical advice here. if your doctor said you specifically can’t take metformin that is one thing. generally all medicine comes with risk, your doctor has to help decide if the benefits outweight the risks on a case-by-case basis.

in general, type 1’s CAN take a medicine for insulin resistance such as metformin. cheers take care!

How do you know if you have insulin resistance? I brought it up due to some darkening of skin in my armpits after I read that’s a major clue you’re having it but my endo didn’t take it super seriously and just told me it was part of having diabetes. I saw a derm to rule out any skin conditions but she told me what was going on wasn’t dangerous or anything to be concerned about, and that losing some weight and lowering insulin may reduce skin darkening but that it’s also common and to not worry about it unless it gets worse. She also said it might just be related to everyday friction. I have good control, but I feel like I take a lot of insulin to keep within range and my ic ratio is a lot higher than other diabetics I know. Obviously not looking for a diagnosis but how do you get your endo to look at it?

Hi @Tee25 Taylor I am not sure who you’re asking so I’ll take a shot.

Everyone has insulin resistance. Everyone. It’s when resistance becomes a problem or it the resistance is causing secondary issues of it’s own is typically when a resistance treatment may be considered. In type 2, when resistance is causing higher blood sugars there’s 2 choices- take additional insulin or take a drug to lower resistance such as metformin. Metformin has risks and side effects so the gains have to clearly outweigh the risks.

For type 1 we are already taking insulin so taking a little more does not add too much risk or new side effects.

I weigh 165 lb and take 58 units a day on moderate carb intake when I am not moving. That can drop to 30-40 total units if I have even some activity or to the lower end if I am very active. I therefore see about 40% reduction in necessary insulin based on activity a portion of which is resistance.

Hope you are ok.

Taylor @Tee25, you are not taking too much insulin for your activity level, and for your food intake, UNLESS you are also. finding yourself constantly in a hypoglycemic state. You appear to have the proper balance of those three items. I currently use about 20 units of insulin per day to balance my activity and the 20++ grams of carb eaten, just about what I took more than sixty years ago. During intervening years, I needed 100 units per day and didn’t notice darkened skin.

You have done right bringing your concern about darkening skin to medical personal - although from my experiences living with diabetes, and talking with others living with diabetes, it sounds as if your doctors might be taking the “easy route” by placing the blame on diabetes. I’m not a medical doctor, so this response may not hold weight.