Trying out Metformin... Wow!


I thought I would update this thread to let people know that my splitting of metformin has been a huge success.

In the week or so since I’ve done it, my estimated A1c on Dexcom has gone from 6.6% to 6.1%. And, what’s more, the number of nights I’ve been able to sleep the entire night with no alarms (high or low) has gone up exponentially.

Before splitting metformin, my overnight pattern often looked like a mountain, with a gradual rise followed by a gradual fall. Since splitting metformin, it’s been a fairly consistent flatline.

The other thing I’ve changed is that I’ve started doing a 1.5 hour extended bolus to cover dinner. If I don’t do this, I’m prone to dropping low after dinner, then treating and going high, then correcting, and we all know what a mess that creates before bed. This allows me to bolus for dinner and be done with it, and oddly I don’t spike high (beyond my upper limit of 8 mmol/L or 145 mg/dl) at all for dinner even though I’m getting no insulin up front.


@Jen, this is truly an amazing result! It is absolutely great to read this!

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I’m so happy to read this! I had a few nights in a row with no alarms after switching to the evening metformin, and it was like a big breath of fresh air! I can totally empathize with your experience.

I’m trying to balance bg levels while on a vacation at the moment, and time zone changes and additional activity are throwing everything out of whack, but before that, evening metformin was pretty dreamy.


This is so exciting to read. I have been interested in trying metformin for awhile and have an enormous inherited (don’t ask) bottle of it in my medicine closet that I’m itching to try out. But will converse w my dr first… I’ve only been CGMing for less than a year, but have noticed a real and significant dawn effect that short of a middle of the night bolus isn’t fixable with insulin alone. Thank you all for sharing – please continue to post your experiences?! (Would also love to hear about any T1s trying any SGLT2 meds…). Thanks! Jessica

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I came to this thread because I thought I’d update again about metformin. Splitting the dose continues to have amazing results, with flatlines most (but not all) nights. According to Dexcom, my estimated A1c has now dropped to 5.9%. That is by far the best control I have ever had while not eating low carb! There have been lots of moving parts lately (Graves’ went into remission, iron deficiency is being treated for the first time in years, sleep apnea is being treated for the first time in years, I have my energy back, which makes dealing with diabetes and everything else much easier), so it’s hard to say whether this improvement is solely due to splitting metformin, but I have no doubt that splitting the metformin dose has helped a lot!

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That is a nice result Jen. Thanks for keeping us updated.


I was looking around the Dexcom Clarity site this morning and really like some of its features. Here’s a really nice illustration of the past two weeks compared to the previous two. You can see how my overnight numbers are significantly better. And I think those significatly better numbers help pull down my daytime numbers a bit (though they could use some improvement).

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So one thing I can say about the split in metformin is that, while it is AMAZING during the non-hormonal weeks, it does absolutely nothing for hormones. Even with upping my basal dose by 50% I still had significantly more highs (and much higher and more protracted highs) over the latter two weeks of my cycle. As soon as things “reset” it goes back to being utterly amazing. I really feel the impact of hormones on my blood sugar is the reason I can never get an A1c below 6%. My estimated A1c in Dexcom is back up to 6.6%. And that’s not bad… It just drives me crazy having to struggle so much with highs and variability half the time when the other half I’m able to do so fantastically.


I’m sorry that it’s no help during part of your cycle. But I am heartened to read you found something that helps during the other part and gives you better control. I’m curious if you stopped taking it all together during the two useless weeks if it would be even worse?

Thanks for sharing about this. I’m guessing it’s going to help someone who’s in need of the knowledge!

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At least you have 2 awesome weeks out of the month :slight_smile: Hopefully that offsets the other less than awesome weeks.


After my recent trip, I’ve decided to switch back to Lantus at my next appointment. My basal needs fluctuated drastically throughout the trip. First, I was running low from all the exercise (average of 22,000 steps/day according to iphone… which I know isn’t accurate, but still…), and then my liver caught up and started dumping all the fantastic carbs I’d introduced (pasta, pizza, croissants, oh my!!!) so I had to raise my basal higher than it’s been in awhile - yet I still ran high any time I sat down for more than an hour, making the plan ride home challenging. Overall, I transitioned down 3 units then up 5… all within the space of 2 weeks. That’s a lot of movement for me!!!

I’m sure that when I switch back I’ll have complaints about Lantus, but I think I’d like to deal with those for awhile instead of the complaints I have with Tresiba. It takes days for my body to catch up to a dose change, and I’m constantly adjusting around my insulin. I honestly started thinking about going on the pump the other day… which I never thought I’d say again.

I can’t run late with Tresiba like I’ve heard other people do because I notice it 12-24 hours later (though a 2 hour delay isn’t a huge deal). I don’t notice the impact of dose changes until at least 12-24 hours later either. So I feel totally trapped into the dose I gave 1-2 days before.

Maybe I’ll change back to Tresiba one day, but I need a break. I remember how much I loved Tresiba when I first tried it, so I find it really interesting/strange that my feelings have changed so much. Maybe I’ll switch back to Lantus and remember all the reasons I loved Tresiba :smile:


I had similar problems with Tresiba… I started out running super high and put my dose up to 40 units… Then started going low so lowered it to 20 units, and things seemed OK there for a few days, then I shot up super, super high again… Knowing that my basal needs fluctuate by about 50% every two weeks, I think that was a big part of my problem. If I ever want back to MDI I would definitely use Levemir, because I don’t think anything else would be able to keep up with my basal fluctuations.

When I miss a single dose of metformin I run quite high for the day. So I’m sure metformin lowers my overall insulin needs. I think taking it half the time and not hte other half would mess up either half. However, it might be interesting to only take it during the difficult two weeks and not the easy two weeks. Maybe then my insulin dose would fluctuate less.

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It’s been a few months since I started Metformin now.

Overall Results:

I would say that overall I’m averaging 108-112 mg/dl. This is about a 5-10 mg/dl drop in my averages from the 3 months prior.

My 90 day average gets a little messed up by a really rough week in the end of February when I was in Italy. My basal needs jumped by 5-6 units and my average bumped up to 122 mg/dl. I think two weeks of pasta and pizza caught up with me :smile:

I think my standard deviation is the more impressive statistic. It’s dropped about 5 mg/dl. I’m consistently running a standard deviation of 26-31 mg/dl for each 2 week period. The total standard deviation over the last 90 days is 34 (largely due to that week the end of February).

Ongoing challenges/observations:

Contrary to my expectation, my basal needs fluctuate a bit more while on metformin. I’m still working on understanding the variables involved.

Before starting Metformin, I had a 1-2 unit basal need variation depending on the time of the month and activity levels.

Now, I’ll go through times where my basal needs are at 20-21 units/day for a 1-1.5 week-long period, then it’ll jump up to 24 units/day. 24 is still 1 unit lower than my lowest basal needs were prior to starting Metformin, but that’s a HUGE jump from 21 units.

I don’t think it’s entirely attributable to my activity levels (though I suspect they play some role). It may be due to carb intake, but I’m not really sure. I suspect that it’s due to hormones, but the patterns are very different than hormone patterns I’ve previously had. In addition, my prior hormone patterns don’t seem to be occurring - I’m not sure if it’s because they’re obscured by whatever this other variable is or if my basal needs due to hormone levels have changed… if that makes any sense.

Anyway, I’m going to start recording when my basal need changes occur so I can hopefully determine the causes and see how they relate, if at all, to my monthly cycle. If they do relate, I promise to post it on the hormones thread @T1Allison :slight_smile:

I still have some nights where I run a little higher, but I respond to my insulin and understand the causes when this occurs. Overall, my evening spikes, when they occur, peak at much lower values because I can control them. It’s still my most challenging time of the day, but I feel like I can control it much more easily.


Looks great!

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That is breathtaking, @Katers87. Super happy for you!!

That’s right! Accountability City here for the cause of the sisterhood!! :grin:

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When I was (miss)diagnosed as type 2, I was taking invokana and metformin 1,000mg twitce a day. then DKA occured… hospital, switched doctor, diagnosed as t1 and then he (the doctor) took me off both pills and put me on insulin.

He told me that there was a time in which metformin was banned because of some issues with patients dying (didnt even know… havent researched that myself yet).
I have read that invokana is known to have some nasty side effects.

So anyway… I’ve been tempted to take metformin to see how I react in conjunction with insulin… but Im a little scared to do the experiment.

Dr also told me that if I ever switch to another doctor I should say to him/her not to give me metformin… I guess I should follow the indication.


Congratulations on better control with less insulin.

I’ve also felt like metformin has perhaps sort of “emphasized” my hormonal changes. But I can’t put my finger on how. A bit ironic, as I originally started it because I was interested in seeing if it helped with my hormonal fluctuations.

I would try to stop and see what the change was, but every time I miss even one dose my blood sugar skyrockets to crazy high levels. So it’s clearly doing something, and I already have a pretty hefty insulin dose even with metformin, so I don’t really want to stop if it means I’ll have to take a hundred units each day. My endocrinologist says not to stop taking it if it’s helping my blood sugar. (Again, ironic as he originally didn’t think it would make any difference!)


I haven’t read anything like this. On the contrary, nearly every study that includes Metformin lauds at least one of it’s attributes. I’ve only read one or two negative studies that contradicted all the other studies (which is seemingly par for the course with any studies) - none of which included the drug killing patients. Metformin is not recommended for people with significantly impaired kidney function (along with a lot of other drugs). Otherwise, there are only a few cautions (such as not drinking heavily).

Metformin has helped me significantly, so I want to be very clear to anyone reading this that the statement your doctor made is INCORRECT. If you have a study or even a news article to provide to back-up that statement, then I’m happy to discuss that. But a comment like that (even without anything to back it up) can scare people from using a medication that might actually help them quite a bit. Sorry if I’m coming off a bit harshly.

Metformin is the most commonly prescribed drug to treat type 2 diabetes. It’s incredibly different than Invokana which is an SGLT-2 inhibitor.

I would not be willing to take Invokana unless I had severe insulin resistance and could not control my bg levels any other way. I’ve read many reports that link this drug with foot amputations and kidney problems. If you search it on fda. gov , you’ll see all the many warnings.