How long does fast-acting insulin REALLY work?

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1

So I've noticed that on movie nights, which basically means dinner, movie, and dessert, Sarah is always high. Last night we had burritos at around 6:30 (she took insulin twice because she decided to have two burritos). Probably around 8:30 we interrupted the movie to eat dessert, and even though Sarah's dessert was about 45 grams of carbs, her pump only gave her 0.05 units because it showed she still had 1.55 units on board from dinner.

After the movie was over, around 10pm, she tested at 270. So I am wondering if I should adjust her pump to 3 or 3.5 hours for the insulin.

Does anyone else have any experience with this?

 

2

I don't know what kind she uses, but according to http://www.apidra.com/fast/what_type_of_insulin.aspx?WT.mc_id=APWB139&WT.srch=1&gclid=CKain-nVoKUCFQg3gwod4hWSHw

  • Rapid-acting (mealtime) insulin - begins to work about 5 minutes after injection and continues to work for 2 to 4 hours.
  • Regular or short-acting insulin - usually reaches the bloodstream within 30 minutes after injection and is effective for 3 to 6 hours
  • Intermediate-acting insulin - reaches the bloodstream about 2 to 4 hours after it is injected and is effective for 12 to 18 hours
  • Long-acting insulin - reaches the bloodstream 6 to 10 hours after injection and is effective for 20 to 24 hours. One type of long-acting insulin is Lantus® (insulin glargine [rDNA origin] injection). It starts to lower blood glucose levels about an hour after injection and works for up to 24 hours. Please see Important Safety Information for Lantus® below.
3

She uses Novalog and from what I've read it has maximum effect from 1-3 hours, but can last up to 5. Her pump is set to 4. Maybe I'll dial it back to 3.5 hours and test that for awhile.

4

I think I may see your problem but I may also be way off. You didn't really clarify how much insulin you gave for the burritos but I think the problem is the .05 for 45 carbs of dessert. I can use my ratio to show where I saw the problem:

Insulin/ carb ratio- 1:10

Burrito 1 (30 carbs) - 3 units

Burrito 2 (30 carbs) - 3 units

Dessert (45 carbs) - 4.5 units

I would end up taking all 10.5 units of insulin even if I had insulin on board. As far as how I treat myself, IOB is really only accounted for with corrections not carbs. Carbs must always be treated with insulin (expect with lows of course). Again I don't know your daughters ratio but it seems to me that she did not receive enough insulin for the dessert. Also, I usually run a higher temp rate during movie nights, because I am usually just sitting and eating the whole time. Hope this helps.

5

[quote user="Dan"]

I think I may see your problem but I may also be way off. You didn't really clarify how much insulin you gave for the burritos but I think the problem is the .05 for 45 carbs of dessert. I can use my ratio to show where I saw the problem:

Insulin/ carb ratio- 1:10

Burrito 1 (30 carbs) - 3 units

Burrito 2 (30 carbs) - 3 units

Dessert (45 carbs) - 4.5 units

I would end up taking all 10.5 units of insulin even if I had insulin on board. As far as how I treat myself, IOB is really only accounted for with corrections not carbs. Carbs must always be treated with insulin (expect with lows of course). Again I don't know your daughters ratio but it seems to me that she did not receive enough insulin for the dessert. Also, I usually run a higher temp rate during movie nights, because I am usually just sitting and eating the whole time. Hope this helps.

[/quote]

Dan, yes. The issue is that when we test her, the pump does the math and takes into consideration three things:

  1. Her current bloodsugar (and it tries to move her back to her "goal", which I've set at 125)
  2. Her insulin-on-board - which the pump calculates using the 4 hour time for the insulin that is currently set (i.e. my dilemma)
  3. The carbs she's about to eat.

So she was a little "low" when we tested for dessert - she was 104. So it looks to me like the pump figured she didn't need the remaining IOB for the dinner carbs, and sort of applied it all forward. My guess though is that the insulin had mostly run its course by that time. So I'm wondering if I should adjust her pump to 3 or 3.5 hours from 4 so it will recognize that the insulin she took earlier has been used.

6

I think Dan is right that she didn't have enough insulin to cover her dessert.

Maybe instead of changing the insuin time (because minimum 4 hours is right for most people), change her target to 110? 

Keep in mind that some Mexican food requires a combo bolus because the carbs are digested slower due to the cheese and sour cream.  That could also explain the near-low and then rise.

7

[quote user="spaghettio"]

I think Dan is right that she didn't have enough insulin to cover her dessert.

Maybe instead of changing the insuin time (because minimum 4 hours is right for most people), change her target to 110? 

Keep in mind that some Mexican food requires a combo bolus because the carbs are digested slower due to the cheese and sour cream.  That could also explain the near-low and then rise.

[/quote]

Okay, I was just speculating that maybe it was the 4-hour thing. So if I'd done the same amount of insulin and a combo bolus, she'd likely have been a little higher, but she'd have still had IOB, so I'm afraid it still would have instructed no insulin. I suppose for dessert in the future I could just do the insulin for the carbs, and not listen to the pump's opinion, lol.

As far as her target. I'm not sure what it should really be. Her doctors set it at 135, but as she's most often lower than that anyway, so I changed it to 125. I'm pretty sure they try to keep kids a little higher so they don't go too low, though Sarah seems to have lows regardless. If I can get her to a place where her IC ratio and basal are perfect so she stops going into the 60's everyday, I might change it a bit more. At her last appointment we looked at the standard deviation of her bg and it was 45; they said ideal is under 50. I'm thinking 45 is pretty close to 50 and I'm gonna do what I can to reduce it a bit more.

Anyway, thanks so much for your help! I really appreciate all the experience and advice. :-)

 

8

I agree that is was probably the lack of insulin for the dessert.  If I ate 45 carbs and only took 0.5 units, I would be high too!  I'm confused as to why the pump would do that.  What kind of pump does she have?

9

[quote user="jessicola"]

I agree that is was probably the lack of insulin for the dessert.  If I ate 45 carbs and only took 0.5 units, I would be high too!  I'm confused as to why the pump would do that.  What kind of pump does she have?

[/quote]

I guess that's really what I'm trying to figure out. I thought it was the issue of still having IOB. Would love to find a "fix" so we don't have to get creative every time we have dessert, especially as not everyone she's with is willing to "get creative"...

10

I've been pumping for 13 years, and it's my understanding that the pump should always give you insulin for the carbs you entered based on your insulin to carb ratio for that time of day.  The only time the pump should be factoring in how much insulin in still in your system is if it's figuring a correction bolus.  For example, if my bs is on target and I ate 45 carbs, my pump should tell me to take 3 units (my ICR is 1:15).  If I'm above target, I should be able to see how much it recommends for a correction, though it may have me take less if I still have insulin in my system.

Also, for dessert ideas, check out www.hungry-girl.com.  They have their own versions of most desserts, and the best part is they provide nutrition info for all their recipes!

11

The whole IOB thing is tricky.  The pump should only be counting IOB for a correction, not for carbs.  That said, I have seen Laura's pump do something similar and subtract the IOB from insulin needed for carbs.  It doesn't always do this but I have seen it.  I always check what the suggested dose is for the carbs and then decide what to do from there.  Sometimes I only dose for the carbs and sometimes I do subtract a little for the IOB.  Remember that the pump's calculations are only a suggestion and you should feel completely comfortable overriding it's dose suggestion because you know a lot more information than the pump such as activity, type of food, etc.  My daughter's IOB time is set for only 2 hours. We started at 3 hours and she always ran high if she ate before the 3 hours was up because the pump wanted to subtract IOB.  Now that she is at 2 hours we don't run into that problem as much.

12

There are a couple settings to consider, and even so IOB is still tricky.

One setting is the carb sensitivity - which is how many points 1 g carbs will RAISE BG. Your endo or pump trainer probably put in a 'default' amount if you didn't know for sure that 15 g will raise her 50 pts or something like that. (I actually don't remember what that is called in the pump.)

The next setting is the amount of time the insulin works - you could try knocking it down to 3.5 hrs and see if it makes a difference. In your scenario this would make it think there was more IOB than there actually was

The third is her target BG. This will have her pump correct her for anything 20 pts (or whatever +/- range you set.) above or below her target. the pump should be ignoring IOB in the total if she is within that range. You could try broadening the range.

If my son is 'grazing' which is what I would consider your example meal, I usually ignore the IOB unless he is low. I know the IOB is working for the carbs he already has eaten and give the full dose for the next item. Also, the type of food you are eating can mess with it. Burritos probably have a good amt of fat, so the carbs will be slower to digest (kind of like pizza) and so she might have ended up high later in the evening anyway.

13

[quote user="JDVsMom"]

There are a couple settings to consider, and even so IOB is still tricky.

One setting is the carb sensitivity - which is how many points 1 g carbs will RAISE BG. Your endo or pump trainer probably put in a 'default' amount if you didn't know for sure that 15 g will raise her 50 pts or something like that. (I actually don't remember what that is called in the pump.)

The next setting is the amount of time the insulin works - you could try knocking it down to 3.5 hrs and see if it makes a difference. In your scenario this would make it think there was more IOB than there actually was

The third is her target BG. This will have her pump correct her for anything 20 pts (or whatever +/- range you set.) above or below her target. the pump should be ignoring IOB in the total if she is within that range. You could try broadening the range.

If my son is 'grazing' which is what I would consider your example meal, I usually ignore the IOB unless he is low. I know the IOB is working for the carbs he already has eaten and give the full dose for the next item. Also, the type of food you are eating can mess with it. Burritos probably have a good amt of fat, so the carbs will be slower to digest (kind of like pizza) and so she might have ended up high later in the evening anyway.

[/quote]

Thanks! I did decide to adjust her sensitivity, though I adjusted it up, from 100-130, because I noticed she was constantly going low after corrections. I'm thinking I probably should have just used my head and added more insulin when she had the dessert, but it was close to bedtime and I'm always a little fearful of giving her too much before bed. Generally the pump settings work pretty well! I didn't really think about adjusting the range of her target, that's certainly something to consider. I did adjust her target down a little, from 135 to 125.

I do what you do when she's grazing. For example, if she's 71 before dinner we'll put in the carbs and let the pump do the first calculation, but if she decides to eat another 20 grams, I skip the bg part of the calc so it doesn't do it again.

Actually since the dessert incident she's been pretty darn good. Yesterday was insanely good, 153 at breakfast, 128 at lunch, 127 at dinner, and 130 at bedtime. Weirdly good! Today was pretty good too, 111 at breakfast, 88 at lunch, 190 at dinner (I think this was because she ate about 2 hours earlier than usual), and 160 at bedtime. Might tweak her I:C ratio back down just a smidge for food eaten after lunch, but will wait until the weekend because she has shows all week in the evening and being up on stage with all the lights and stuff tends to make her low.

14

With burritos, I usually do a combo bolus. When I do a straight bolus, I end up low two hours after eating and HIGH (ok, so ~300 isn't that high) four hours after eating. With a combo bolus, when I end up eating within the time of that bolus, I ignore IOB. 

So, she's low-ish at 2 hours, but about to rise, and also eats dessert, which she doesn't get enough insulin for because of the pump's semi-unintelligent method of calculating IOB (you use animas, too, right?). That's what I imagine happened. 

If she had eaten something like potatoes or white rice for dinner, something that is all simple carbs and no protein/fat, and two hours later was at 104 with IOB, I might have used the pump's suggestion, because I know that simple carbs will be almost all in my system by 2 hours after eating. 

In other news, diabetes is hard. 

15

I agree that the most likely cause was probably too little insulin for dessert.  You could also definitely lower her target.  Mine is 130 during the night (to prevent lows), but 100 during the day.  Also, I use Novolog and my active insulin time is 3 hours, I'm pretty sure.  Changing the active insulin time and target shouldn't cause huge differences in blood sugar, so you could try those, check IOB, and also try the combo bolus next time she eats burritos.  There are way too many variables in diabetes, lol.

16

For the pump IOB means nothing when you're adding more carbs. The IOB is treating old carbs, if you add new carbs then you need new insulin. I've never ever heard of a meal bolus being reduced because of IOB, only correction boluses would be reduced (or disappear).

That being said... Sometimes I enter stuff in wrong (you're in the middle of a meal, you're grabbing seconds, your pump pops up an extra screen because it's mid bolus and all the sudden I've entered my carbs in accidentally as my BS). Sounds like whatever happened... you were suspicious at the time. Trust your gut, sounds like you have a great understanding of what should/shouldn't be going on with her doses.

So it was just a fluke, and I think we all know that flukes happen a lot (at least they do to me!:) I too worry about going low for bed, so I can understand being careful around dinner time.

Since Mexican food can have a lot of fat I typically use a dual-wave bolus, so I deliver about 50% right away, and then deliver the rest over 1.5 hours. That might help, but it's definitely something that has to be experimented with. Without CGM it's hard to really understand mexican food! I think her high dessert numbers might have also been because of dinner, in addition to a lower bolus. I frequently find if I flub 1 meal... then my numbers for my NEXT meal look bad (even though it was meal number 1's fault).