Basal Rates and Hormones


Day 15: +5% was not enough last night. It worked all day, but last night I drifted up to 190 at 3AM. I took a correction dose. I came down to 160 and it drifted right back up to 190. Now I’ll try +10% as I get closer to ovulation.

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We’re back in full swing here with hormones and blood sugar.

This time around, there was a +20-30% rise and fall in basal needs (and insulin needs all around). I just experienced “the drop” about two days ago.

My Fitbit predicted the timing within one day. Having that is very useful for confirmation of my suspicions and helps me make faster decisions to raise or lower basal rates or other settings.


My BG is very sensitive to activity, and when I started podding, I remember how thrilling it was to discover how a 5% reduction might be all it took to spare me hours of running low. I’d love to see what happens with even a 1% or 2% drop (not that it’s possible).


My thing recently has been doing a “poor man’s low suspend” where I suspend my pump if I’m, say, under 6 mmol/L and have a lot of IOB. It’s surprisingly effective at preventing lows as long as I catch it in time. I can’t wait till it’s automated—I think it will work incredibly well for me!

Just last night I was 5.7 mmol/L heading to bed with I believe 1.25 units of insulin on board (or maybe it was 0.75 units, can’t remember). Either way, it was enough that I knew I’d end up low in an hour if I left it. I suspended my pump for (I think) an hour and a half (using a 0% temporary basal, so I didn’t have to worry about turning the pump back on). My blood sugar dipped and brushed my low limit, but then rose to 7.0 mmol/L and stayed perfetly flat at that level for the rest of the night.

It doesn’t always work that well, sometimes I still go low and sometimes I skyrocket. But overall, I’d say I have about a 75% success rate.

(For exercise, if I exercise hard during the day or more moderately during the late afternoon or evening, I do a -10 to -20% basal rate for eight to ten hours overnight, which really helps to prevent lows. Again, sometimes I use this when it’s not needed and end up high. But overall, it’s quite helpful.)


Further proof that we were separated at birth. Last night I was 4.2 and dropping slowly at bedtime with 4.60 on board, so I temped 0% for 30 minutes and had a couple of cookies. Dipped to 3.3 by an hour later and then slowly climbed to 7.8 over the next 2 hours and hovered around there till I got up. I’ve done -75% or -50% before, but I actually wanted to be slightly higher this time.


Also adding this post here for general reference:

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Ok, @T1Allison, I made it! And I’ve read through all 250 comments, phew.

I’ll use Nicky’s little setup:

Number of years with diabetes: 16
MDI or pumper: pumper, 670g
CGM? medtronic guardian and dexcom g6
Diabetic during reproductive phase of life? perimenopause? menopause? Reproductive - I’m 22
Did you notice any insulin resistance or sensitivity due to hormonal changes? Yes! more so sensitivity during period
How did it impact your bg control? Your diet? How did you manage it (or not manage it)? I just didn’t manage it and ate more treats
Do you use hormonal birth control? What kind? Yes. Mirena IUD
Do you experience insulin resistance or sensitivity due to hormonal changes while using birth control? Not sure. I wasn’t really monitoring my diabetes before and I’ve had it for years so I believe my insulin needs are way different now I assume

Ok, I have so many questions and points of confusion I don’t even know how to organize and get it all out there. Nevertheless, she persisted.

I’m assuming there’s another thread for birth control separately but I’m running a little low now and don’t have brain power to go searching and reading…

However, even though I’m on Mirena, I still think I sort of “qualify” for tracking hormonal changes and insulin needs over the cycle (and thus I think it makes sense for me to be in this thread (if you want to move me that’s fine :slight_smile: ). 1. because I am ovulating (even with Mirena, women ovulate). 2. I have noticed insulin sensitivity (not sure about insulin resistance) across the cycle

I’m planning to write up some stuff on the Mirena and how I believe my hormonal basal needs may differ since I am on it (again please feel free to be like "Larissa you’re late to the party - we’ve already done that!) and I’m planning on tracking basal needs and using temp basals across the cycle, founded on the framework in Allison’s original post

I’ve downloaded the app Clue because I’m really terrible about writing down and remembering when I start my cycle.

I am planning on doing this and tracking with the app !

Dropping this picture down here mainly for my own reference but also if anyone’s curious of body temp over the cycle (which I plan to write a blurb on - again direct me to someone’s post if it’s been done here before!)


Ok with all that, and because I’m low and whiny - can I just say it’s SO annoying that us ladies have to worry about this?!?!? And that our needs change nearly every day and that every month it’s not the same like really?!?

ALSO it’s so insane to me that there can be fluctuations of basal needs from-15% to +40% and this isn’t a thoroughly researched aspect of blood glucose management??? If I get to set up and conduct my own research study in med school I’ll do it on this and you’re all invited to participate


Interesting! My experience is the exact opposite of yours. I have a basal need increase about 1-2 days before my period that lasts throughout my period.

My most insulin sensitive week begins 1 week after my period has ended.


You are not late to the party! This party will go on forever and we’re glad to have more women to party with us!!

Awesome. About persisting.

There is…but we’re always in search of more info on this topic. Since you’re on Mirena, here’s the only other experience on FUD that I’ve seen related to Mirena. You may have a totally different experience.

I would guess so! It will be interesting to see what you find. Mirena uses a second generation progestin locally released in small quantities. My general understanding from my CDE is that it may dampen your insulin sensitivity fluctuations as compared to if you were not using Mirena, but it might introduce the tiniest amount of resistance overall (due to progesterone usually causing a bit of resistance). So, hopefully this means that your cyclical insulin sensitivity fluctuations will not be huge!

I really hope this helps you! Hopefully you will not see large fluctuations, and hopefully if there are moderate to small ones you can track them and adjust for them without too much issue. For me, scaling my basal up and down throughout the cycle with flat percentages is the way to go…but it only started helping me once I had my basals all set to work cohesively according to my Week 2 needs. Since that took me YEARS to figure out from a problem solving perspective, the percentage increases and decreases exacerbated problems that existed within my basal profile. All of which is to say, watch out for any trouble spots. Something that is a noticeable spike or dip in Week 2 for me became much larger when I added a percentage change to it in Weeks 3 and 4.

Great idea. I use the Fitbit app for this same thing.

Yup! Preach. I wish mine only changed during PMS or during my period, but that is simply not the case for me. And maybe we’re all different. And maybe I’m an extreme example. But sharing our experiences together will help continue to answer those questions since we’re getting no help from the medical experts.

[my hand is shooting up to join this project in any capacity you need at a future date]

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This just confused me… because I am not 22. The rest I was worried I had maybe written, and lived, but had just forgotten.

Got it now. It’s you. With my picture. :grin:

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O, wait HAHA. It took me a while to figure out what you were talking about. Just fixed it :sweat_smile:

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This is what I’m guessing as well because of the progestin!

Ugh, yes. Haha sooo much basal testing to do and so little time over those few days in week 2!

But yes! Cheers! I feel like a pioneer on this one, which is pretty cool. Let’s just publish a paper with our FUD’ers data (sample size of 6?) I feel like Nature will take us


interesting! I feel like it’s got to be dependent on all our individual hormonal fluctuations. So crazy, but I’m looking forward to really tracking my sensitivity/resistance so I can add my trends!

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I was cool with being 22 and having that kind of handle on my hormone understanding… I just wasn’t sure you wanted to be me. :grin:

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Wait, so brief recap of cyclical hormones (just making sure I get this right) and how they may relate to blood sugar/insulin activity. Each hormone’s actions:

  • Progesterone = increase in insulin RESISTANCE = decrease in insulin SENSITIVITY = overall higher blood sugar
  • FSH and LH and estrogen - this is a big question mark? But I’m guessing because of some documented elevated sugars during ovulation that -->
  • FSH and LH = increase in insulin RESISTANCE = decrease in insulin SENSITIVITY = overall higher blood sugar
  • Estrogen = increase in insulin RESISTANCE = decrease in insulin SENSITIVITY = overall higher blood sugar


Please correct me if I’m wrong!


It’s not necessarily that simple, since some reactions are to hormone withdrawal (or other fluctuations in the hormones), and not just to the hormone level per se. At least that’s true with most other effects of hormones (on mood, behavior, physical symptoms), so I’m guessing could be the case for insulin sensitivity and other metabolic factors. I see increased insulin resistance during high estrogen parts of my cycle and increased insulin sensitivity specifically during progesterone withdrawal, for example.


I don’t know that anyone knows for sure. Pregnancy D books discuss how increasing progesterone throughout the pregnancy increase your need for insulin. And that your drop in progesterone in the first trimester causes the drop in insulin need (which was fairly significant for me). So I’d say that it’s generally understood that progesterone causes insulin resistance. My cycle experiences definitely support that.

Estrogen I’ve never gotten a straight answer on from anyone. The last time I asked an expert, they said that the ovulation spike in insulin needs that I see is from the other hormones in addition to the estrogen…like FSH and LH, I assume?

If anyone finds any detailed literature about this topic, I would love for it to be shared on one of these threads.

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Looking at explanations of the decrease in insulin need in first trimester:

CONCLUSIONS —Observations in the DIEP cohort disclose a mid–first-trimester decline in insulin requirement in type 1 diabetic pregnant women. Possible explanations include overinsulinization of previously poorly controlled diabetes, a transient decline in progesterone secretion during the late first-trimester luteo-placental shift in progesterone secretion, or other hormonal shifts. Clinicians should anticipate a clinically meaningful reduction in insulin requirement in the 5-week interval between weeks 7 and 12 of gestation.

I find it interesting that “overinsulinization of previously poorly controlled diabetes” gets first mention, followed by decrease in progesterone, then other hormonal shifts as the potential explanation.

I see the routine theme in female diabetes topics that the researchers don’t know the answer, but their top hypothesis is typically to blame the patient for poor control in some way. Yet the researchers still themselves don’t understand the mechanisms. So we’re supposed to understand the mechanisms and be well-controlled why?


It’s a reach but if you experience increased insulin resistance in the few days before and after ovulation then it could be pointing to estrogens role in added resistance since LH and FSH are pretty notorious for peaking in a smaller time frame around ovulation

I’m going to go on the hunt for literature on these hormones even if it’s more in vitro style because I’m just so amazed at the complexity of all these hormones and how they interact (and how there’s an absence of clinical studies here :face_with_raised_eyebrow:)

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