ISF varies by blood sugar?



Generally, I’ve found that when correcting for a higher high (>200), I’ll flatten out slightly above my target (which is 100) to about 130-170 range. When correcting for a mild high (150ish), I’ll flatten out below my target to be around 55-80. These are just trends I’ve noticed and I haven’t officially tested them or anything, but I’m guessing there’s either some insulin resistance when you’re higher or something going on? Does this happen to anyone else? Have there been studies on this phenomenon (if there is one)?

Do you adjust what ISF you’re using depending on what your # currently is?


Your experience matches our experience. When above 300, we often have to use 5x or even more to drive the blood sugar down. You can’t just use one ISF for all blood sugars and have it work correctly. Yet another of the mysteries that CGM’s are helping us manage and test for.


Wow 5x?? I definitely should be more aggressive with my upfront correction when I’m in the really high range because I’ll end up trying to correct each 15 minutes and will end up low…


Same as @Chris: when you are very high, you need more units per mg/dl of correction.

But—you also have to be careful that it also takes longer (at least for us) for insulin to become active. If you are too quick to press the trigger on stacking, you can easily end up with too much insulin. For istance, it takes typically 45 minutes for insulin to be activated for my son. But, at 250+, it may take up to 2 hours sometimes, in particular for hormone peaks. So if you stack too quickly you can end up with a sustained low.


I should note that the most common reason we are above 300 is growth hormones, so my experience may not exactly match your current situation, but we would definitely use more than 2x for above 300. Some of the hormone highs have even required 8x.


I definitely adjust, for highness and for time of day. For me, a daytime high-high requires around double the usual correction dose, and at night it’s triple or more. (This is one area where my guesses are usually accurate.) I also find injected nighttime corrections are more effective than bolused. My highs are entirely due to carbs, not hormone peaks.


Imagine someone stumbling on this post and thinking your are talking about pot. It would be hilarious.


@Michel aaaaaaand now I know what you all mean by stacking insulin LOL


@Beacher does this reflect your personal basals? As in your basals are higher at night?


@Chris :rofl::rofl: I used to be high 24/7. quite the stoner


Ditto everyone elses’ sentiments. When Liam’s high, I double any normal requirement for insulin and sometimes even 3 or 4x as much.


My overnight basals are higher, yes. For much of the daylight hours my basals are between 0.2 and 0.55, and overnight they’re in the 0.7 to 0.9 range.

On my pump I can set different ISF’s for different times of day but not for different BG ranges. Do any pumps do that?


I notice the same. If I’m nudging a BG down before it’s actually high, it often only takes 0.25 or 0.5 units. If I’m high at 11+ mmol/L, it often takes substantially more to get me to even budge.

The old Cozmo pump had a feature where it would automatically apply an additional percentage of correction for higher BGs, based on your settings. So the higher you were, the more correction insulin could be applied (or not, if you didn’t want to use that feature, and the settings within that feature were very customizable).

I really miss that pump. It had better features than any of today’s pumps even though it’s now more than a decade outdated. Hopefully that feature will show up in a newer pump at some point.