Variance in insulin throughout the month

How much does your insulin dose vary, especially for women? This is out of pure curiosity, since obviously everyone is different depending on diabetes type and insulin sensitivity and whether you have any insulin production left and so on.

Since starting on the Dexcom, I’ve found that my insulin doses shift dramatically about twice a month. I sort of knew this before the Dexcom, but since getting it I’ve realized just how dramatic it is! And it really does happen overnight!

For example, yesterday and today (over the past 36 hours) I’ve experienced “The Drop” as I call it. In that time, I lowered all my basal rates by 0.3 u/hr, my I:C ratio went from 1:8 to 1:12, and my ISF went from 2.0 to 2.8 (36 to 50). And I’m still running low-ish and having to eat extra carbohydrates with no bolus on occasion, so I may end up lowering some things a bit more, though I’ve managed to avoid most lows, with the exception of almost all of yesterday morning, because I acted so quickly.

Since starting the Dexcom, sometimes I’ve anticipated hormones falsely and changed settings only to have my blood sugar go high or low because I shouldn’t have touched anything. I’ve found that having my basal rates off by 0.05 u/hr can make the differnece between me staying in range constantly and me running at 11 mmol/L (200 mg/dl) constantly. I’m not particularly insulin sensitive, but it seems like my body has some minimal threshold for basal that, if I cross, I can’t get highs down no matter how much I correct until I put my basal rates back up.

And yet, when my basal rates need changing because of hormones, they change dramatically—and fast. Over the past few months I’ve found that my insulin dose changes by 20-25 units overnight twice a month, once upward and once downward. Unfortunately, not totally predictably, so it’s not something I can put on a calenard and have a formula for.

I’ve decided to give the opposite of The Drop a name, probably something like The Rise, because I picture an evil being rising from the depths. I need to get more aggressive at attacking it when it appears, but I’m always nervous that it’ll be one of those times that I’m just imagining things and I’ll crash really low. The one great thing is that, with the Dexcom, I’m able to keep my average lower than it ever was before, even during the weeks of chaotic highs.

Anyone else? I’m guessing I’m not alone in this monthly insanity.

My insulin need goes up quite a bit, like 15%, for about a week before I start my period. Other than that any changes throughout the month are random, short lived, and very small.

I have noticed this last month, though, since I’ve been on Metformin for insulin resistance, and birth control to even out my very messed up hormones, that my period insulin increase wasn’t so drastic. Hopefully this will continue to improve as my PCOS gets under control.

I’m still figuring out all these issues and working with my doctor to understand what’s going on with my body and what’s helping what, etc.

I am guaranteed several units of basal shift throughout the month (2-4 units) even if my weight doesn’t change. If my weight shifts over the course of the month, the basal change can be dramatic, maybe 8 units. I adjust basal upwards 2 to 3 units up when I get my period.

The most rapid, least explainable, and least predictable increases in basal requirements are during exercise and after waking. Basal requirements seem to taper off more slowly after exercise. They taper pretty quickly off after going to bed.

25 units overnight does sound like a big shift. Geeze. When I did that big, extensive test, some months ago, I found that I had to cut my morning basal by almost half, at night. Basal requirements might quadrupel during exercise, or they may remain constant. I’ve tested all of this while fasting over the course of months. The variability is pretty tough. I had to test it and test it in order to believe what I was seeing.

Some of the guys say that the level of variability might decrease and the system stabilizes, somewhat, after age 40. DP gets less pronounced and you don’t have the same kinda hormonal surges day in and day out. One, possible good thing about aging.

Here’s one of the best models in the world for BG control. They have been working on this for decades and they can only do 15 min predictions. The BG system is complex and ‘noisey.’ http://jp.mathworks.com/matlabcentral/fileexchange/48019-blood-glucose-regulation-in-a-type-i-diabetic-in-simulink

Did you see this post, Jen? Just noticed it for the first time today.

I hadn’t seen it, but I downloaded it to try it out. I’m skeptical that it’ll be able to predict anything I can’t already predict myself. My problem isn’t the predictable stuff, it’s the NON-predictable stuff!

Last night I spent over eight hours low, staying mostly between 3.2 and 2.0 mmol/L (57 and 40 mg/dl), despite eating almost 100 grams of carbohydrates without bolusing. I was honestly beginning to think my pancreas had come back to life, but when I finally was able to go to bed, I proceeded to go low again…then my pump proceeded to run out of insulin. I was so tired that I didn’t wake up to either my Dexcom alarming or my pump alarming. Two hours later I did wake up to find that I’d been low for almost two hours and that my pump had been out of insulin for over two hours. The lack of insulin meant that my low was correcting itself by the time I woke up, but it also meant that my blood sugar shot up to 11-14 mmol/L (200-250 mg/dl) for most of the morning along with borderline high ketones (0.6 mmol/L). So I’m still insulin dependent, it seems; so much for my pancreas revival theory.

During the course of those lows I ended up lowering my basal rates by 0.2 u/hr and my carb ratio from 8 to 10 and my correction ratio from 2.0 to 2.5. (Between making this post about the lows and last night’s lowering of settings I had a period where I ran crazy high for days and had to put all my settings up higher for a while…) Sometimes I feel like I change too much at once, but as of this afternoon (once recovered from the high) things seem to be fine—at least I’ve had a flat arrow for the past hour and a half, which is better than I’ve had in the previous 24 hours! We’ll see over the next few if I’ve overreacted by changing so many settings at once. The problem is that, as you can see on the graph, my blood sugar does not just drift slightly out of range every once in a while and need little nudges in insulin doses…it goes completely insane and goes so far out of range that it takes days on end to get back on track if I just nudge one setting at a time and wait 12-24 hours between changes. And I don’t want to just not change any settings during these times and see if it “blows over” because it never does. When things are so far out of range it means that I’m staying up all night to monitor or feeling crappy all day at work, so I need to change something to try and get back on track. It seems like each time this happens I go about five days or a week with the new settings with everything going fine and happy, being able to aim for a flatline, until my body suddenly decides to change again. My explanation for the rise and then (last night’s) fall in settings is that I was feeling really exhausted and run down all last week, so I think maybe my body was waged in some sort of battle with a virus that it finally won.

Using the CGM has made control much easier because it allows me to spot and treat highs and lows sooner, but it’s also confirmed how utterly crazy my blood sugars can be sometimes and how rapidly my insulin needs can change for seemingly no explicable reason. I try to just deal with things so I can get back on track as fast as possible when my blood sugar goes completely berzerk.

Jesus! Your data looks similar to mine several months ago. Remember? Before I split the basal? I had insulin requirements that were X during the day and X/2 during the night, so there was no one single dose that was going to fix it and I had to split. I know your on a pump, so it gets even trickier, because you have the option for so many dosages.

I also doubt that they can do three hour predictions, like they claim. The problem with making predictions in BG systems is that there is a LOT of chaos and noise in the system. My night time readings looked just like yours some months ago. Are you eating every time it rebounds back up from a low? I ask because I got sooo tired that I would just let the numbers play out and sleep through the bad behavior sometimes. It would make that googy, oscillating pattern. So, I assumed my liver was throwing out sugar when I got low, pulling me back into the normal range, then the basal would nudge me back down. But, my Doc said those overnight, oscillating patterns were just steady, flatline low BG. She said sensor error made it look like an oscillating pattern. I don’t think she believes these strange patterns of behavior exist. Someone told me yesterday that has something to do with American Medical Association. They might not allow a model of our illness to include any inputs other than insulin and exercise, which is a pretty simple model.

Just outta curiosity - what time did you wake up?

How many basal changes do you have in a 24 hr period?

I know there’s a lot going on with your system that’s gonna be hard to figure out, but, of course, I think you gotta drop that PM basal setting, starting at 4pm. Mine had the same pattern - low from 6PM until I woke up in the morning, when it spiked dramatically.

I’m worried about you, Jen. Keep posting data. Sounds like your in one of those extremely confusing, difficult, irritating times when nothing is as it should be.

P.S. Just got a new transmitter today, so Ill download the app and see how good its predictions work for me (I’m not in as rough as spot as you are, right now, but I’m also not fine tuned). Your system might have too much chaos to make any predictions possible at all. But, if it can’t do any predictions on mine, either, we’ll know that the model its using is too simple to be useful. I’ve become obsessed with variability in the data…have been reading this: Chaos.

I woke up at 5:45 and did not treat the low. The high is from my pump running out of insulin. The oscillating pattern of the long overnight low is me eating glucose tablets to try and bring it up. The larger spike is when I finally ate a big bowl of cereal, waited for my CGM to alarm that I was riding, and did a half bolus at that point.

I had the same issues all last night:

At this point, over the course of 36 hours, I’ve lowered my basal rates by 0.3 u/hr firing the day and (as you mentioned already) by 0.4 u/hr from 4:00 through until morning. In MDI terms, that’s like lowering the basal insulin by about 8 units, though obviously it’s not quite equivalent.I’ve changed my I:C ratio from 1:8 to 1:12, and my correction ratio from 2.0 to 2.8 (not that I’ve done any corrections, it just makes sense that I should adjust it if I’ve changed all my other settings).

Right now I have six basal rates throughout the day. I tried cutting back to five, but this didn’t seem to work as well. I skip meals fairly regularly to test basal rates. I don’t think my problem is primarily basal rates, though; I think it’s a true sudden shift in insulin sensitivity that’s due to multiple, uncontrollable factors (hormones, weather, internal factors, etc.).

I’ll see if I can find it, but three or four days ago I was almost flatlining all day. Six or seven days ago I was running high non-stop. Eleven or twelve days ago I was experiencing what I talked about in the original post. It’s insane. But before I used to just feel like I must be missing something obvious. Now I feel like there IS nothing obvious: my body dtruly does seem to change dramatically for no reason. Maybe my body is just ultra sensitive to small shifts that most people only experience as a drift.

So far my new settings seem to be working okay. Here’s hoping I’ve gotten things right for now, at least until they’ll probably change dramatically again in a week…

I think I am kinda like you, but I am really inconsistent, from day to day, with eating patterns and exercise levels, so I’ve never been able to determine if the variability was due to my behavior or something intrinsic to my system. Until, this winter, when I was having such difficult patterns that I quit eating most meals and maintained a sedentary lifestyle. I did that for three months and the variability persisted. Although, I’m sure there was less variability than if I had been exercising a lot. If I had kept skiing, I wouldn’t have been able to ‘keep my hands on the reins of the horse,’ and I would have ended up in the hospital or crashing my car and hurting someone.

I passed out on an insulin pump a lot. I’m super impressed whenever anyone can tolerate one. My problem was that, the system changed so often and so dramatically, that I couldn’t collect enough data to figure out what to do before the system ‘shifted’ again and all my data was worthless. With the split, I can handle dosing two basals - an AM and a PM, with some certainty, off paper calculations. But, any more than 2 doses and I get confused. I need a computer to do the calculations for me. And, I’m super doubtful that a computer can even do those calculations reliably, even for two doses of basal, because of the variability. The variability is the demon - the chaotic nature of the system is the killer.

If you have any breakthroughs, let me know. I’m gonna keep working on it, too.

This is why I love the pump, and even more since getting a CGM. With a pump I can respond to changes very rapidly. With long-acting insulin, by the time your changes take effect you might already be moving on to something else. Plus, for me a single basal level really didn’t work. I think this is why even trying to move from six to five rates didn’t seem to work for me.

One thing I do with the pump is that I usually treat my basal rates as one dose. So I change them all at once rather than fiddling with segments. I will sometimes change just one or two segments, but I play around with that during periods of stability. When the huge shifts hit, I just move all my basal rates up or down. I used to only make one change of about 0.05 u/hr each day, but since getting the CGM I’m becoming much more aggressive, like changing basal rates by 0.1 u/hr every 12 hours or so until I’m back on track. I don’t think my basal pattern shifts that much, just my level of insulin semsitivity.

I do find that a consistent schedule helps a lot. I measure it weigh everything I eat, I eat roughly the same things at the same times each day, I try not to snack between meals, and I try to get a similar amount of exercise each day, and I have a consistent sleep cycle. I can’t be a robot, but I can keep things mostly consistent a majority of the time.

Yep, that’s right. I remember. You are fast like a rabbit, and I am slow like a turtle. You make lots of changes all the time, compared to me. I might make one, minor basal adjustment, stand back, and watch how the system does in the next 30 days. You use basal, like I use bolus. Your doing more real time adjustments. That makes the conversation get real confusing. I’ll have to remember that. What does your sensor offer you as a measure of standard deviation? I think my Dex gives a couple different measurements. I’m hoping to measure if that number is smaller, now, than the number I had over the winter when there was LOTS of variability. I have some work to do to figure out how they calculate that, but no matter what, I would guess it is smaller than it was. SInce I’m running a low A1c, that gets to be a critical measurement. A few months ago, I hit 5.8, and there’s no way that was gonna fly.

This is a good song for a busy rabbit on Friday! I love this song. Run Rabbit Run!

As in 5.8 was An unacceptable A1c for you? Two months ago I was 6.1, which is by far the best A1c I’ve ever had. I’ll be curious what it is next month. I think my standard deviation and average might be slightly higher, but overall I feel like I’m understanding more. I’ve only had the Dexcom since late January, and the first six weeks of data isn’t on my computer since it was a loaner unit, so I don’t have very much data to look back on.

Too low an A1c to support my high level of stdev. That’s the argument from the Doc. Doc thinks I’m giving myself brain damage. (Last night I checked at 3am and BG = 45 mg/dL= 2.5 mmol/L by your measurement, but woke up at 335 mg/dL = 18 mmol/L). I’m sure I need to cut the basal dosages down, for the summer, but otherwise, feeling pretty good. Neither the Doc or I, knows for sure, what is too low a standard deviation because nobody has really looked at the data. Its all just “blah, blah, blah.” But, her point is definitely worth investigating, if I figure out how. Doc’s office is making the claim that more than 2 hypos in a week is too many (that’s gonna relatively impossible for me to achieve, no matter what). What does your Doc say about all this???

I would think the lower the standard deviation the better. I’m sure @acidrock23 and @Terry4 would agree, they are both amazing and (I think) that’s what they aim for over averages. I’ve read somewhere that the SD should be 1/3 of the average or lower than 30 mg/dl. My standard deviation for the past week is 2.8 mmol/L (50 mg/dl), which is not 1/3 of my average or less than 30 mg/dl, so it’s too high using the standards that I’ve read. But it’s lower than it was two weeks ago, and it’s lower than my average SD for the month, so I’d count it as an improvement.

The last time I saw my doctor in April he said that my numbers were some of the better he’d seen. My numbers have been more variable lately, but I suspect he’d say the same thing because they aren’t that much worse. I get my A1c done in a couple of weeks and see him in a month, so it’ll be interesting. I’ll ask him what he thinks about all these rapid changes (still having issues with lows, even though I’ve lowered my TDD by ~20 units over the past few days!).

Thanks for your data, Jen. Once I get my transmitter, I’ll be able to figure out mine…and see how it compares. Yea, let me know your A1c, when you get it, and what the Doc thinks about it. My Doc is a little on the hysterical side about lows (American lawsuits, ya’ know). Also, her educator said she would hook me up with a Dex rep if I had any ?'s, which is super helpful.

Lower is, of course, better. But, Dexcom calculates it many different ways, ‘whats acceptable’ gets a little open to opinion. AR posted his, so thats a good reference. Also, that new software has some good reviews, and they might give a calculation of variance/stdev. I’m super interested in that, in particular, because me and the Doc want to try out a few different basals, and compare them, to see if one produces less variability than another. There’s a new basal, similar to Ultralente, out.

20 units is a huge pile of insulin! Good for u!

Re the StdDev questions posed, I forgot I have an actual source, which I received through Tu, “Insulin Pumps and Continuous Glucose Monitoring A User’s Guide to Effective Diabetes Management” by Dr. Francine Kaufman has a brief discussion of StdDev and suggests that it should be less than 55 mg/dl or less than half your average glucose level (pp 42-43, if anyone wants to track the book down.). It’s a pretty good read I thought.

@mohe0001, have you read Sugar Surfing? I’m just reading it now and this quote made me think of you:

It’s important to understand that many forces drive blood sugar levels up and down within the bloodstream. The concept of Sugar Surfng is based on the acceptance of chaos in biological systems combined with the desire to make adjustments proactively and react to unexpected BG changes before things get out of hand.

Also, the author likes to set his pump to one single basal rate throughout the day. It’s a really great book so far (I’m about halfway through).

Cool, I have NOT read. Thanks for the recommendation, AR and Jen. Will read. @Jen, hows that software working out? I still haven’t gotten my transmitter…

I’m still working on figuring this out and it’s annoying. Just when I thought I had it, things changed even for the basals I’d set previously. Somewhere during the 2 weeks preceding my cycle I have to adjust my IC (particularly during lunch hours). But this has not been consistent. One month I had to change my basal and IC ratios 2 weeks out, another month my numbers were okay until one week out, then another time things didn’t get wacky until like 2 days before- just frustrating because I’d love if I was changing things up at the same time each month.

Other thing which I’ve realized is that I can’t jump to make a switch right away because it could be an air bubble causing the higher number, so I usually wait 2 days to see if the same thing happens. Bottom line- I have variances that generally come somewhere around my cycle, but it’s just not the same time frame month-month or the same needs (in terms of basal amount or IC).