Teens: variability in Correction Factor and Insulin to Carb Ratio

We have always seen a lot of variability in both Correction Factor (CF) and Insulin to Carb Ratio (ICR) when my son’s basal needs change. Possibly because we are looking at it so carefully, we are now noticing significant changes in both CF and ICR without basal changes.

For once, my son’s basal needs have been fairly stable for the past 3 weeks, even with changes in training regimen. But we have seen, over the past two weeks, a radical change in CF and ICR. His CF has decreased by a factor of two: he needs half the insulin he needed before for an average peak correction. Because these corrections are normally very large, the difference is quite significant. For something that may have needed 15 units 2 weeks ago he may only need 7-8 units or less right now.

Similarly, the ICR has changed, in the same direction, but nowhere near in the same ratio. If he was 1:13 at dinner, he may now be at 1:17.

We are trying to link this change to something concrete. His exercise level has gone up a bit, and is a bit more regular. It is possible that this may be the reason. But the difference is not major, so we are not sure.

The most unusual part of it, for us, is that this change did not come with a change in basal. We checked to make sure that it is not simply a tolerance in the basal insulin levels. When we decrease basal insulin by 10%, he does trend high, and when we increase basal insulin by 10%, he does trend low. So his basal need is truly unchanged.

Cortisone both increased my basal needs but also very noticeably increased my I:C (basically, I was much spikier) and correction factors. So my guess is steroid hormones (i.e., growth and reproductive). At least once he’s past his teens, his won’t be cycling every month, since I think it’s a factor and major impediment to tight control for many naturally cycling women.


That would make plenty of sense.

@katiereeder, I think your boy and mine are pretty much exactly at the same point of development? How much variability do you see?

Anecdotally, with crazy hormone ivf meds, big impact. I almost doubled my tdd in 2 weeks… now its dropping back again but next med cycle will start soon. Its a mess. Hit 200+ every day for the past 2 weeks. No lows and insulin amounts that are fairly scary to me. I’m so glad my t1 came after puberty and I got a couple decades left til menopause. Its amazing the “kids” do so well with all those extra variables.


Yeah, well once you have children, those decades will pass so fast it will make your head spin. Careful what you wish for…

It is hard to believe my first will be a senior in HS next year…I think I am getting old.

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I’d say we probably have to fiddle with ICRs and correction ratios every 3 months or so, and it doesn’t always come along with big changes in basal needs (his true “fasting” basal in the middle of the night in particular always seems to be around 0.9-1.0 even when other things are changing). Regular exercise definitely decreases insulin needs in our case and it doesn’t have to be a sports season – just if the weather warms up and he’s playing outdoors more. I figure there are so many moving parts between growth patterns, him getting into short term habits of certain snacks and lunches, what activity they’re doing in gym class, etc…I’m trying to get in a very systematic groove of pulling the 7 days dexcom data on the same day each week, looking at trends then making one or two small changes to tweak stuff instead of sort of ad hoc-ing it, will see if that helps.


I should have also said we find growth-spurt fueled spikes (for a while he was spiking sharply while asleep, presumably due to growth hormone release) to be waaaay harder to crush than regular “junk food” spikes, not.responding to the same correction ratio…so if your guy’s current fluctuations are related to puberty/growth hormones, that might make sense that the usual corrections aren’t working.


2 posts were split to a new topic: How to test and set ICR and CF