Active Insulin Time (Duration of Insulin Action?) Basics For an Experienced Diabetic Noob

That was interesting. Thank you for the link. In it one comment talked about how it was irresponsible of the doctor to recommend a change from 3 hours to 2 hours. I’m just curious… was it?

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If I remember correctly, Kerri was post-pregnancy with kiddo #2 and had been dealing with a lot of highs. Her doctor suggested changing the DIA/AIT as a last resort to deal with those highs.

For me, I would have to try a lot of other things before I try that. I always try to get to the “why” of the problem when deciding on a solution. I cannot imagine a scenario for myself wherein artificially changing the DIA/AIT setting would be the answer. It certainly leads to more aggressive correction dose calculations, but it’s not getting at the real meat of whatever the real problem is because unless I try a new insulin, I don’t see Humalog’s duration going down to two hours on a consistent basis.

In my body, Humalog seems to last three hours when I’m pretty darn active…pushing to 3.5 hours. When I’m super sedentary, I feel like it lasts closer to 4.5 or 5 hours. Fortunately (or not), my control still isn’t quite tight enough for that calculation difference to make huge differences in my results just yet (i.e. if I was running closer to 90 all the time, I’d see more advantage to the calculation being closer to reality. But I’m still averaging high 140’s, so I have a lot more wiggle room).

Just to clarify: I’m not a looper. I don’t think Kerri was a looper in the blog post I linked to. So as far as IAT and looping, @TiaG is the source of great info. I’m only commenting on DIA in general since it sounded like you had questions about that, too.

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I think it makes a huge difference and is one of the main levers to pull when you’re using hybrid closed-loop systems. We found with Samson that there was no way to avoid unanticipated lows with a DIA of 4-hours… we upgraded it to six and eliminated those bizarre phantom lows. The issue with these closed loops is you’re stacking upon stacking insulin at an enormously frequent rate. So a difference in 30 minutes in your DIA could mean that you will invariably tick up in the last hour or two of DIA, or that you will inexplicably plummet when there’s supposed to be zero or even negative IOB.

But, in my opinion the DIA isn’t that useful for manually administered correction doses at all. That’s because sometimes you just need so much more insulin for the same number, and to me the main factor determining how much you need is how sticky that number is and past experience. So a high of 200 from overtreating a low with juice will come down with much less than 1 unit of insulin. A high of 200 from eating pizza will take 2+ units to bring down. If we’ve already issued one correction and things are not dropping like they should, we just give between 20 and 50 percent more than we might otherwise. And in the end, you want to come down quickly and that’s easier to do with just overbolusing and feeding the tail anyways. The little bit extra in the tail won’t be a huge hassle to compensate for, usually just another glucose tab.

To me, the rate of change from the last number is the best indication of how much insulin is needed. WE give 0.4 units if Samson is rising +8 or +9, 1 unit if he’s rising +15, and so forth.

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I use a DIA of 6 hours in AndriodAPS, which is a realistic number. I do not correct highs using a bolus calculator so the IOB is just used as a gauge of how much insulin I have on board.

DIA also depends on what pump you are using and how IOB is calculated. So my AndriodAPS DIA is 6 hours, my Omnipod DIA is 3.5 hours. Omnipod uses a linear curve for IOB (i.e. a 4 hour DIA will mean 25% of the insulin is used ear hour) while Andriod APS uses a curve that is not a line (that takes into account the time it takes for the insulin to peak and then the time it takes to absorb). The non-linear curve means more insulin is used up front and for the last 3 hours of my 6 hour dia, there is just a small fraction of the original dose left.

The problem with a traditional bolus calculator is it tells you how much insulin you need based on IOB and the difference between your current BG and your target BG… BUT in many cases you may need more insulin.

So… I think people who use IOBs that are less than 6 hours are either using an Omnipod, or are making a choice to me more aggressive with corrections when they use a pump bolus calculator.

I usually do not use a bolus calculator to calculate how much insulin I need to correct high BG. I just guess how much insulin I need based on the CGM trend. This often looks like giving 2 units or so every 1/2 hour until I see the CGM trend change in direction. If it is a steep change I give more, if it is a slow change I give less. If I am really high, I just give lots. This usually results in getting enough insulin to correct the high. (and sometime too much so then I have a cookie to cover the IOB).

So the only time I use IOB is to eat cookies or take glucose to prevent a low when I overcorrect :smile:

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@Aaron, @TiaG, and @T1Allison, I just wanted to let you know I’ve read all of your responses and really appreciate your taking the time. I want to respond but have been really busy. I’ll shower you all with unnecessarily long responses as soon as is humanly possible… just don’t want you think it was an “ask and run”. :smiley:

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Do not let me get in the way of running :running_woman:

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If you WERE in the way, you’d have plenty of time to get out of it. :smiley:

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My endo has been adjusting my Active Insulin Time. (670g with Guardian sensors.) It’s now up to 5.5 hours. I understand this is a long time. However, once I get used to the new time, it does work better than what it was before.

Jack

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Hi @Jack! That’s interesting… sounds like your endo is going the opposite way with your AIT on your 670G. Usually they they head in the other direction and take it all the way to 2.5 hours. Are you in Auto?

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@Nickyghaleb are you doing it again with @Jack?

BTW, where did you ever land on the DIA/AIT discussion? 2.5…6?

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You know what’s funny about this? Is I was like if I say something, will I be accused of doing it again with Jack? :rofl::rofl:

And, no, I’m not doin NUTHIN, thank you. :face_with_raised_eyebrow: Just a 670G enthusiast doing 670G chitchat stuff. :thinking:

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3.5. Never budged. Now if you want to hear all about it, you’ve been around long enough to hear it. :grin: Seriously, my endo wouldn’t adjust mine because she didn’t like the premise, and then a call to Medtronic confirmed the decision.

That’s the short version. The long version is a LOT more exciting. :grin:

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Most likely… But only cuz we (me?) kinda like you like a younger sister. As an aside, I’m reading your post and CCR is on the radio playing “I put a spell on you”, so maybe there’s some hidden truth?

Now Chicago is playing on the radio - “Does anyone really know what time it is?”. Weirdness… FWIW, mine’s 3.25. I use this number in the face of all logic because the bulk of my bolus is done by then. An insulin tail is just extra goodness. OK… Enough

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I’m not sure I qualify as everyone’s “younger” sister around here. Unless we’re talking years in maturity. That might make sense. :grin:

That’s that 670G magic. Gonna put a spell on you alright. :rofl::rofl:

All this talk about it, and I’m starting to miss it. I might call Medtronic today just to hear that music. Do a little reminiscing. :thinking:

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I am proud to say, and I hope @Eric is listening, I do 3.5 hours strictly because my endo told me to. It’s one of the very, very few things left that she gets to hold onto. :grin: Well, that, and all the prescription power and all my copays and now a global fee I will be handing over to her at every appointment… but that’s it.

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AHA stoooooop. Wanna trade??? Because you miss the 670g so much

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9 posts were split to a new topic: Global Fee’s - What the Heck

I would be looking for another Endo…

Yes, I hardly ever use the Manual mode. BGs keep going down during the night for up to 5.5 hours, even with Auto shutting off the micro-boluses.

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So Auto is running you too low, @Jack? Just out of curiosity, how are the rest of your settings in comparison to what they were like in Manual? Your ISF and carb ratios? Did you make any significant adjustments to those since starting in Auto?

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