Trying out Metformin... Wow!

I’ve had a pretty active past couple of weeks (mostly the 1st week), so I can’t give Metformin all the credit!!

Still, I’ve never had such a low average and low standard deviation over a two week period… ever. I started 500mg/day ER Metformin about a week ago, and my late evening spikes have nearly disappeared (the primary reason I tried it out was because I seemed to be experiencing insulin resistance in the evenings). I’m seeing some lows in the early morning though, so I’m reducing my basal dose by a unit today. That will be my lowest basal dose in the last 9 months, assuming it works alright.

This next week is generally my best week during my monthly cycle, so I’m not sure if I’ll be able to conclude much from it.

As a sidenote, my endo ran some tests related to why my A1c and eAG don’t match up. Everything checked out, so there’s some additional good news.

I’m going to update this thread based on how things progress on the Metformin. I’m on a really low dose, so I’m surprised I’ve seen benefits already. We’ll see if that lasts. I haven’t experienced any nasty digestion side effects yet. We’ll see if that lasts too.



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I also started metformin a couple years ago with similar results. My reason for starting was studies that show reduction in risk for cancer reoccurance, so also on low dose 500 2x per day. I had to reduce insulin a bit, and some minor side effects, but otherwise has continued to help with BG more stable and predictable.


Look at how beautiful that line is :slight_smile: I tested my bg when I woke around 6 am because I didn’t believe it. Meter was only 2 mg/dl off.

Observations since last post:

  • When I’m sedentary, Metformin still helps with my insulin sensitivity in the evening, but the effect is less pronounced. I’ll peak at 160 with a medium carb meal on a sedentary evening (on Metformin) rather than 200 or 210 (off Metformin). I went through a period of time where it didn’t seem to matter how much insulin I took, I was going to go up past my normal range and not respond to insulin like I would at any other time of the day.
    If I exercise, then I remain insulin sensitive when I’m not active (no peaking to 160) in the evening. I seemed to have lost this in the evening for awhile, and it’s been a bit frustrating. The line above is a day when I exercised, so no peaking. I’m really pleased with the lack of oscillation. Usually if I get a flat line like that at the beginning of the night, I fight lows all morning (3-8 am).
    Exercising always helps. Always.

  • I’m thirsty more often.

  • I’ve only had mild digestive discomfort on one day- not even sure that’s related to the Metformin.

I just realized that the G6 doesn’t post the numbers on the right when you display a 12 hour graph. Since I took the photo around 6 am, I have the lower bound set at 70 and upper bound set at 160. I was hovering in the 80s all night.


Wow that is really awesome! The Metformin appears to have really evened things out for you. I can’t even imagine a line like that with my son. Fantastic result.


I’m tempted to try Metformin combined with MDI to simplify BG control but am paranoid about losing weight…I don’t want to. It seems like I have to stick with relatively high carbs (200g +/- daily) and protein (a lot) on MDI just to maintain my ideal weight (170 lbs). I’ve read that many people experience weight loss on Metformin. Have you noticed any trends with your weight since you started Metformin?


I’ve also read that Metformin can cause weight loss. I don’t actually weigh myself on a day-to-day basis, so I can’t really tell you if I’ve lost weight. I started Metformin to see if it would help with bg control, but I wouldn’t mind if I lost weight.

I’ve only been using Metformin for a very short period of time, and I’m on a very low dose. Even if I do lose some weight while using Metformin, I wouldn’t expect that to happen for some time. I suspect it would be more gradual if it happens at all.


I lost about 12-15 lbs when I went on metformin, but I was over my usual weight and suspect that weight was due to increasing insulin resistance. I feel like metformin changed things so that weight, which had been extremely stubborn until then and slowly but steadily increasing, was suddenly easy to lose. It did not, however, make it easy to lose weight once I got down to what seems to be my body’s typical set point (which is still higher than I’d like, but where my body seems most content to settle at, historically). Metformin just made it so my body is back to its normal pre-insulin resistant state, basically. So I suspect metformin’s effect on weight may be dependent on whether you have weight that’s attributable to insulin resistance or not, and if you are struggling to maintain weight, you probably don’t.


I’ve been dealing with lows any time I walk anywhere or am mildly active, and it’s becoming really, really annoying. I walk or metro everywhere, so it’s practically a constant problem.

I’m also dealing with lows in the early morning. I’ve suddenly become a lot more sensitive to insulin, so I’m working on adjusting my doses. I’m using almost half as much insulin at mealtimes.

I dropped my basal another unit this morning. That makes it 2 units lower than my lowest dose at this time of the month (since going off birth control). I’m guessing I’ll need to drop it another unit though.

I’m frustrated, but I’m trying to keep the perspective that there’s always an adjustment period. I want to see how well everything works once I’ve dialed in my basal properly. I’m hoping dropping my basal will make a big difference.

It seems like it took a full two weeks before metformin was at full effect (maybe not even at full effect yet?). I was not expecting this dramatic of a difference at 500 mg/day.


I experience this problem, too, with the exception of the morning. I didn’t even think that it could be caused by metformin. Though, I’m fairly sure I experienced this same thing even before starting metformin.

I’m on 2,000 mg a day but didn’t notice any enormous impact. I still go high, and my insulin sensitivity didn’t change all that much. I just went through a week or so where my insulin sensitivity was hugely increased (like I was taking 2 units for something I used to take 5 units for, and a 0.25 unit correction would drop me by 3-4 mmol/L, and I ran a -30% basal for days). Last night I was back to being high and that’s lasted through today, so whatever was causing that has passed.


I experienced it when my basal was too high before Metformin, and I’d see a very gradual decline when my basal was the right amount. The drops are pretty dramatic right now. I’m hoping my basal is still too high so that this goes back to the more gradual decrease I used to see once I’ve reduced my dose enough…


I’m not seeing the drops now. I’m not getting the beautiful line above at night either. However, I am more sensitive to insulin all the time.

I’m going to hold off updating the thread for a week. I’m thinking I’ll have a good grasp of the benefits/drawbacks of using Metformin by then.

Some good news is that I’m not experiencing any digestive side effects yet. I guess I dodged that bullet.


It’s been an interesting week with Metformin. I’m actually still trying to figure out a lot.

After dropping my basal dose (to 23 units), I stopped having the drops, but I started trending upward all the time and having bigger peaks after meals. I considered stopping metformin altogether because it was clearly not helping with the problem. I bumped my dose back up a unit (24 now) so I had sufficient basal.

Then I acccidentally forgot my morning metformin dose!! I had several important meetings that day and didn’t want to make the trip home. I ended up researching a bit online, and I found out that metform XR peaks about 6 hours after ingestion. By 12 hours, there’s only a low level amount left (if I’m understanding the graph below correctly). If you’re fasting, it peaks and declines even sooner.


I decided to switch my dose to the evening (at dinner) which worked out conveniently because I’d forgotten my dose that day anyway. The next couple days were pretty chaotic bg wise. I think missing a metformin dose is a really big deal. Maybe if I’d been on Levemir I could’ve simply increased my Levemir dose for a day or two, but that doesn’t work as well with Tresiba. I just rode it out and things started to normalize about 36 hours later.

If I’m going to stay on Metformin though, I cannot miss a dose!

Now I’ve only had a couple nights with the evening Metformin dose, but I am seeing an impact. It’s really helping. I’ve been able to keep the same basal dose (24 units). I’m not seeing drops during the day while walking at all (my current theory is that it’s because the Metformin has mostly worn off by then). I went for a 45 minute walk yesterday, and I just had the normal slight decline I used to have.

These are my takeaways at this point:

  1. Metformin should be taken so that it is peaking (or at least pretty active) during the time frame you suspect you have the most insulin resistance.
  2. An overall basal insulin dose decrease may still be necessary. I’m suspecting that I’ll be able to maintain my 1 unit/day decrease.

What I’m still learning and trying to figure out:

  1. How Humalog and Afrezza are affected by Metformin (for me). I don’t have solid conclusions on this… just a bunch of theories. Afrezza is not acting the same for me though. I plan to research and test this more.
  2. I think Metformin (taken in the evening) might make me more sensitive to alcohol? I know that there’s a risk of lactic acidosis while taking metformin and drinking. After trying my best to research online, I decided that drinking 1-2 glasses of wine was fine as long as I hydrated well. I don’t think I’m experiencing lactic acidosis (it seemed that this was relatively rare). I didn’t notice any difference when I took my dose in the morning, but I suppose that makes sense because there would’ve been less metformin in my system by the evening. Anyway, just something I’m watching.
  3. I have experienced some slowed digestion (constipation) over the last couple of days (since I switched my dose to evening). Hopefully that either is unrelated or doesn’t stick around.

Fantastic post @Katers87, that is a lot of great info in one place. I hope you get this dialed in to you liking soon.


Thanks Chris. I hope it helps someone else if they decide to give Metformin a try.


This is super useful information! I’m on Glumetza, which I thought was just like an extended-release version of metformin. After doing some reading, it seems it’s a little different than other versions of metformin. But I assumed it lasted for 24 hours. I take 2,000 mg in the morning (two pills). After reading this, I’m wondering if I should split the dose so I’m taking one pill in the morning and one pill in the evening to get more even coverage.


It does appear to peak around 7-8 hours according to the FDA paperwork. May want to talk to your physician or pharmacist about this.

That’s very helpful Chris. It also says this:

“At usual clinical doses and dosing schedules of metformin, steady state plasma concentrations of metformin are reached within 24-48 hours and are generally < 1 µg/mL.”

Does that mean that the action time is not necessarily important once you’ve been taking it regularly?

I wonder if there’s a similar document for Metformin XR. Looks like the chart I posted above was for 750 mg of Metformin XR. I wonder if the peak would be different for 500 mg.

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That is why I would discuss it with a physician/pharmacist that is knowledgeable. I am not sure.

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WOW! That is great! I have had good results with metformin, but not that good.

What I really miss is an SGLT-2 inhibitor. It would not allow my Bg to go over 200 ( unless I abused it’s ability). I had to discontinue Jardiance because it increased my creatinine too much. But it was fun while it lasted.