How do pumps calculate IOB?

[twodoor2]

Is there a specific formula, I can't imagine they would automatically know this value based on the insulin delivery since every child is different.

[zimbie45]

yes they do! But you can set the time frame for it to calculate... so you can customize it to you! SO if you know that your insuline is done doing its job in 2 hours.. then you set it to that... if it takes 4 hours.. then it will calculate that long..

hope this helps

[twodoor2]

yes they do! But you can set the time frame for it to calculate... so you can customize it to you! SO if you know that your insuline is done doing its job in 2 hours.. then you set it to that... if it takes 4 hours.. then it will calculate that long..

hope this helps

Okay, that's good, but does anyone know the exact formula it uses to do the calculations. For example, if I tell the pump it takes 3 hours to use up all the insulin, does it come back and tell me a percentage of the insulin left, the exact number of units left, and if so, how does it come up with that calculation?

[WestinsMom]

I think you an find a break down by manufacturer in "Pumping Insulin".

[Kaylee's Mommy]

Okay, that's good, but does anyone know the exact formula it uses to do the calculations. For example, if I tell the pump it takes 3 hours to use up all the insulin, does it come back and tell me a percentage of the insulin left, the exact number of units left, and if so, how does it come up with that calculation?

It does come back with what is exactly left, and it knows for how much longer its left for.. I'm assuming it takes the total units that you give, and divide it by the total time that it takes for it to go through your system.. Kaylee is typical 3, some are 2 and some are 4 or 5.. whatever that calculation comes out to be is what it uses... I've gone to give a bolus and had .5 units left.. 15minutes later they'll only be .4 units left.. also you can give a square wave or a dual wave, this lets you set the time frame and percent of how much you want to give now, and how much you want to give later, and over what specific time frame, and it keeps track of ALL of that.. I can look right on one of Kaylee's screen and see that her square wave has been going for 3 hours, total that is GOING to give, how much is HAS given and How much is LEFT to give.. again, I'm assuming it takes the total amount of insulin divided by the amount of time you want it to figure out how much to give and when..

they are just like little computers.. it amazes me what you can set and do with a pump.. I can actually down load all of K's pump and her endo can go online, get everything, and they can tell when I override, and how much I've overridden it for, any site changes and all the nitty gritties that I didn't know they knew LOL...

[Nancy in VA]

It has a formula - I think its "front loaded". We have a 5 hour duration and I know for sure that it doesn't just take the dose and divide it by 5 to figure out the IOB

But, while we have it set to 5 hours, we know that after dinner, her body only uses it for about 2 hours, so we have to override the IOB when doing corrections sometimes.

[funnygrl]

This actually varies from pump to pump. Some do it linearly, assuming an equal amount is used up each hour. I believe the Cozmo works this way. It basically says if your duration of action is set for 4 hours, 25% is used up each hour (if set for 3, 33%, etc). Others, like the Minimed, I think, use more of a curve assuming more is used up in the beginning, with a tail towards the end. Like someone else said, Pumping Insulin explains it well.

Pumps also use IO differently in bolus wizard equations. Cozmo & Animas will subtract it from carb and correction boluses, while Minimed just subtracts it from correction boluses (so for example, if you typed in that you were 60, had 2 units on board, and were going to eat 10 grams of carb, it would recommend you bolus for those 10 grams if you're not careful). I have used a Cozmo and a Minimed and religiously used the bolus calculator and each and really noticed little difference with my blood sugars, I just sometimes have to use my own judgement and overrule.

Also, some pumps let you set IOB in half hour increments, and some don't. When I was on the Cozmo I used 3.5 hours and it worked well. On the Minimed I use 4, and that works well. In Pumping Insulin John Walsh says you should set a longer duration on the Minimed or Omnipod than on the Cozmo, and Animas. I really recommend that book.

[Nancy in VA]

Pumps also use IO differently in bolus wizard equations. Cozmo & Animas will subtract it from carb and correction boluses, while Minimed just subtracts it from correction boluses (so for example, if you typed in that you were 60, had 2 units on board, and were going to eat 10 grams of carb, it would recommend you bolus for those 10 grams if you're not careful). I have used a Cozmo and a Minimed and religiously used the bolus calculator and each and really noticed little difference with my blood sugars, I just sometimes have to use my own judgement and overrule. .

Animas only takes it from the correction bolus. It assumes, rightly so, that if you eat a certain amount of carbs, then you need to dose for those carbs regardless of what your BG reading is. It takes the IOB into account for a correction. For example, I went to correct a 400 at 3 hours after dinner last night and it actually said the correction was 0.05 after IOB - basically nothing. I overrode that because I knew she needed some, but if I had put in carbs with it, it would have included the entire carb dose and then adjust the correction accordingly. I had to explain that to my husband several times before he finally understood the concept and how it worked.

[Kaylee's Mommy]

Pumps also use IO differently in bolus wizard equations. Cozmo & Animas will subtract it from carb and correction boluses, while Minimed just subtracts it from correction boluses (so for example, if you typed in that you were 60, had 2 units on board, and were going to eat 10 grams of carb, it would recommend you bolus for those 10 grams if you're not careful).

MM WILL subtract from carbs eaten IF you put in your BG, if you do NOT put in your BG it doesn't know what you have left and will just bolus for carbs.. If Kaylee eats dinner, she is 200 before dinner, eats 25 carbs, it will correct for that 200, cover all 25 carbs, and then 15minutes later if she has another 10 carbs I do NOT put in the 200, just the 10 carbs it'll cover for that.. if in 1.5 hours she is 100 and has .5 active, I give her 20 carbs (equals 1 unit for her) it'll take into consideration that she is 100, and that she has .5 active, and will subtract that from the 20 carbs given and will give her less, it WON"T give her the full unit.. but if I skipped that step of putting in the 100 bg, it won't KNOW what she is so it'll give that 1 unit and cover the entire 20 carbs.. :)

[twodoor2]

MM WILL subtract from carbs eaten IF you put in your BG, if you do NOT put in your BG it doesn't know what you have left and will just bolus for carbs.. If Kaylee eats dinner, she is 200 before dinner, eats 25 carbs, it will correct for that 200, cover all 25 carbs, and then 15minutes later if she has another 10 carbs I do NOT put in the 200, just the 10 carbs it'll cover for that.. if in 1.5 hours she is 100 and has .5 active, I give her 20 carbs (equals 1 unit for her) it'll take into consideration that she is 100, and that she has .5 active, and will subtract that from the 20 carbs given and will give her less, it WON"T give her the full unit.. but if I skipped that step of putting in the 100 bg, it won't KNOW what she is so it'll give that 1 unit and cover the entire 20 carbs.. :)


That's pretty scary!! Does it warn you and tell you it's subtracting the IOB from the carb bolus if you do enter the BG? Can you even eat 10 carbs after eating ten minutes prior??? I thought that was a "no no" even in the world of the pump. I always wait three hours between all meals and snacks. If you're bolusing for 20 carbs and correcting at the same time, can you even eat another x amount of carbs a short while later? That's new to me. If the pump can do that, then why not with syringes??

[TripleThreat]

you can eat 10 minutes later pumps only use fast acting insulin and thats the difference

[Ali]

You can do anything with a syringe that a pump does except adjust your basal insulin delivery rate. The bolus/correction stuff is the same. The pump just is an easy caculating machine. You can always choose to do what ever you want with a pump. It simply suggests a dose and then you do what you want. I often adjust the suggested bolus dose on my pump based on what I know my exercise schedule has been, my meal timing will be, etc. You always contol how much bolus to give. The basal you set but you can always change the amount being delivered. It is easy. Ali. P.S. It is just easier to correct with the pump than to give another dose via syringe and easier to adjust the basal becuase it is being driven by short acting insulin. This is easier than trying to deal with having given a shot or shots of long acting insulin that you cannot change if you or your child gets ill half way through the day or night , or you go on an unexpected bike ride, or your hormones change, etc. etc.

[Kaylee's Mommy]

That's pretty scary!! Does it warn you and tell you it's subtracting the IOB from the carb bolus if you do enter the BG? Can you even eat 10 carbs after eating ten minutes prior??? I thought that was a "no no" even in the world of the pump. I always wait three hours between all meals and snacks. If you're bolusing for 20 carbs and correcting at the same time, can you even eat another x amount of carbs a short while later? That's new to me. If the pump can do that, then why not with syringes??

It breaks it down for you on the estimation page and lets you know exactly what its doing,why its giving so many units (or .10th of units) why its adding or subtracting.. its doing its job to make sure you don't give to much insulin.. you can definitely give insulin after eating just 10 minutes prior because the pump is keeping track of all insulin that is given.. if you bolus for lunch, adding in her bg, if she wants to eat again in 10 minutes (which is standard for Kaylee, we just bolus as we go along) then I DO NOT put in her BG again because its already taken that into account 10 minutes ago and either given extra for a high, taken away for a low or left everything alone.. if its corrected either way you don't want to correct again, that would result in to much or to little insulin.. so I have a rule that I don't add BG in for two hours.. if she keeps eating, we just keep bolusing for the food she's eating. :)

while Kaylee was on MDI she she wasn't to eat within 2 hours of her last insulin.. 1 it was easier to keep track of her last dose for correcting.. and 2.. it cuts down on the number of shots.. i supppose if you are very very maticulous about keeping a record and knowthing the EXACT time and amount of insulin you gave, and can figure out whats left/active you can give injections more frequent.. one fo the reasons we went to a pump is the fact that she could 'graze throughout the day... thats just the type of kid she is.. sometimes, especially at a party or family gathering,she gets bolused ALL day long.. its easier now with the cgms, we can actually SEE what she's doing..

[funnygrl]

Ok, I'm almost positive MM doesn't subtract IOB from a carb bolus, and that's the pump I have.

Animas I've never used, so I have no clue.

John Walsh does a better job explaining than I:

http://www.diabetesnet.com/diabetes_technology/insulin_pump_bolus.php

[Lee]

Ok - I'm going to quickly pipe in...

My dd us 155 for supper, the pump gives her 3 units for the meal and .5 for the correction.

It is now 8 pm, time for a test and she is 79 (she has to be above 100 for nightime). I give her a 15 c juice and some pb crackers - 23 carbs.

The pump figures she still has .6 IOB, so it figures out her I:C amount, then takes away for low to get her above 100, and then takes away for the IOB...

Way to smart of a machine!

Oh, we are Minimed

[Nancy in VA]

Ok - I'm going to quickly pipe in...

My dd us 155 for supper, the pump gives her 3 units for the meal and .5 for the correction.

It is now 8 pm, time for a test and she is 79 (she has to be above 100 for nightime). I give her a 15 c juice and some pb crackers - 23 carbs.

The pump figures she still has .6 IOB, so it figures out her I:C amount, then takes away for low to get her above 100, and then takes away for the IOB...

Way to smart of a machine!

Oh, we are Minimed


Do you always give snacks AND dose when you need to get above 100? I would always just give less carbs and leave it uncovered.

The way the Animas works I think is a little different. Our target is 140 +/- 40, so basically 100 to 180. That means it won't correct if you put in a BG between that range. BUT, if you put in a BG outside of that range, it corrects to 140. So, if I put in 90, it would correct to 140 (the target) instead of 100 (the low end of the range). I kinda like that as I consider it a bit more of a "buffer" than when we did MDI and we were correcting to the low end of the target.

[twodoor2]

Do you always give snacks AND dose when you need to get above 100? I would always just give less carbs and leave it uncovered.

The way the Animas works I think is a little different. Our target is 140 +/- 40, so basically 100 to 180. That means it won't correct if you put in a BG between that range. BUT, if you put in a BG outside of that range, it corrects to 140. So, if I put in 90, it would correct to 140 (the target) instead of 100 (the low end of the range). I kinda like that as I consider it a bit more of a "buffer" than when we did MDI and we were correcting to the low end of the target.

I have a formula for IOB, but the number changes every half an hour. It seems the formula that the pump is using changes IOB every minute/second???

Let me just clarify, can you can have a different IOB one minute or every second? I have a degree in mathematics, and I wonder what formula the pump is using. It's just something I would really like to know. I can play with it our pump, and perhaps deduce the formula, but it would be nice to have it. I assume no one really knows the formula. The formula I have gives specific percentages of insulin left, but again, it only changes every half an hour. It also seems these formulas are different depending on the pump, and why???? Maybe they have their own proprietary formulas, and I'm sure it's based on the bell curve provided by the insulin manufacturer. I also wonder if the formula changes depending on what type of fast acting insulin is used since those bell curves are slightly different. Something I need to ask the pump educator about. I know, I know, probably more information than I need to know, but that's just me.

I'm sure because of this formula, the fact that the basal can be adjusted, and the precise units you can deliver with the pump, it's probably a better choice for insulin delivery if you want accuracy and you have greater insulin sensitivity. I'm just a number cruncher, and it always fascinates me how algorithms work, in this case, for the pump.

[Nancy in VA]

I haven't looked at the IOB at specific times enough to notice but I can probably do that over the next day or two to see how the Animas does it. I think its more "real time" than every 30 minutes. And, I hope it kinda follows the bell curve that the manufacturer publishes because that's a little closer to how it actually works, at least for us, than a straight lined distribution - I think it does based on some of the figures I've seen but I'm not sure.

[BrendaK]

Here is a slide presentation by John Walsh which coveres very specifically your questions. http://www.diabetesnet.com/diabetes_presentations/bolusdifferencebypump.html

Hope that helps!

[Nancy in VA]

That's a great briefing. I read it before we were pumping but it makes a lot more sense now that we've been pumping for a while.

I wonder if the Animas 2020 works just like the 1250. It "seems" to based on their breakdown of bolus recommendations based on readings, but I'm not 100% sure

[Lee]

Do you always give snacks AND dose when you need to get above 100? I would always just give less carbs and leave it uncovered.

Yep- most of the time - although I have been known to only put in 3/4ths or something. The Minimed will only try to bring her up to 100, even though her range is 100-200

The way the Animas works I think is a little different. Our target is 140 +/- 40, so basically 100 to 180. That means it won't correct if you put in a BG between that range. BUT, if you put in a BG outside of that range, it corrects to 140. So, if I put in 90, it would correct to 140 (the target) instead of 100 (the low end of the range). I kinda like that as I consider it a bit more of a "buffer" than when we did MDI and we were correcting to the low end of the target.

I would like to have a target instead of a range, that might be one benefit of the Animas that I haven't seen before...

[Kaylee's Mommy]

Ok, I'm almost positive MM doesn't subtract IOB from a carb bolus, and that's the pump I have.

Animas I've never used, so I have no clue.

John Walsh does a better job explaining than I:

http://www.diabetesnet.com/diabetes_technology/insulin_pump_bolus.php


if you are 72 before you eat, and you go to bolus it WILL subtract from the amount of insulin it is going to give Kaylee...

for example

bg 72
carbs eaten 30
estimated total 1.4u
food was 1.7
correction was .3

it subtracted the .3 for correction

or

bg 81
carbs 30
estimated total 1.2
food would have been 1.5 but it subtracted .3 for its correction.

Sorry, I just reread your post and realized that you are talking about IOB.. for some reason I thought you were talking about subtracting from the carb bolus for a low blood sugar.. you are correct, it does not subtract for IOB... it'll only subtract from the carbs when you are below your target.. :)

[twodoor2]

I would like to have a target instead of a range, that might be one benefit of the Animas that I haven't seen before...

Yes, but the down side to a negative correction like that is that it tends to make highs. I was doing negative corrections when she was in range (80 to 180 is our range) in order to get to the target blood glucose - 150. The endo told me not to do that, and I think it helps in our case althought YDMV. We tended to get less hypoglycemia. I think you should have the choice with the pumps to add the negative correction or not, or I guess, by just doing the food bolus, you can avoid the negative correction. Is that true?

[Lee]

I was doing negative corrections when she was in range (80 to 180 is our range) in order to get to the target blood glucose - 150. The only time I think I would like a target is at bed - I would love to say correct or neg correct to 140...that would be perfect, and that is what I aim for by adjusting the pump
We tended to get less hypoglycemia. I think you should have the choice with the pumps to add the negative correction or not, or I guess, by just doing the food bolus, you can avoid the negative correction. Is that true?

You can always adjust what it wants to give your child. That, to me, is the hardest part of the pump - learning to trust it. It does take away from the Bolus if she is low, but I could override that if I decided. But since Bolusing for food isn't the same as stacking corrections, I do let her eat after another 10 minutes, that is a definite PRO to the pump.

If she is at 80 at bed, and I give her the standard snack, then I can decrease her insulin Bolus to make her run around 140, because it tries to do 100...if I am lucky!

[Nancy in VA]

Yes, but the down side to a negative correction like that is that it tends to make highs. I was doing negative corrections when she was in range (80 to 180 is our range) in order to get to the target blood glucose - 150. The endo told me not to do that, and I think it helps in our case althought YDMV. We tended to get less hypoglycemia. I think you should have the choice with the pumps to add the negative correction or not, or I guess, by just doing the food bolus, you can avoid the negative correction. Is that true?

I haven't experienced extra highs this way. Actually, the corrections have been doing a good job of hitting us right at 140. And, with a two year old, I'm more comfortable correcting to 140 than to 100 because its too easy to drop low after that.

All of the pumps give you the choice of what you dose. It will provide a calculation for you and then you dial in the dose (or adjust it, based on which pump you choose). Let me give you an example with the Animas:

BG: 328
Carbs: 52
I/C ratio: 18:1
IOB: 0.6

Calculations:
Carb bolus: 2.9
Correction: 0.85
IOB: -0.6
Recommended Dose: 2.9 + .84 - 0.6 = 3.20

But, lets assume that the IOB was 1.0 and do it again:

Recommended Dose: 2.9 + .85 - 1.0 = 2.9 recommended dose

Basically the 1.0 IOB cancells out the .85 recommended corrrection (correctoin to 140) - so it just recommends the carb bolus of 2.9

OK, lets assume she's low (no IOB taken into account)
BG: 90
Carbs: 60
ISF: 225
Target: 140
Range: 100 - 180
Same I/C

Carb Bolus: 3.33
Correction: .22 (correction for 90 up to 140)
Dose: 3.1

If it only corrected to 100 (low end of range), it would only take off 0.05, which is basically no negative correction for the low. That would, technically if the I/C is perfect, bring her right back to between 90 and 100, which is not a range I like her to hover in - I'd rather her hover in the 120-150 range. That's why we correct to 140

[jules12]

We have the minimed and we have our target range set to 140. When it was set to a range (i.e. 80-120 first and then 100-120) - it would still only correct to the bottom number and would start us going back downward especially during his honeymoon period.

[Nancy in VA]

We have the minimed and we have our target range set to 140. When it was set to a range (i.e. 80-120 first and then 100-120) - it would still only correct to the bottom number and would start us going back downward especially during his honeymoon period.

Yeah, that's my fear and why I like that the Animas corrects to the target #. Especially when they are young. I'm sure when they are older and the units that they are getting are so much more, a little doesn't make as much of a difference.

[Kaylee's Mommy]

if you have a target range, like 140-160 if you are ABOVE the 160 the pump will correct you to the 160, if you are BELOW 140, it will correct to the 140, if you are inbetween it'll do nothing.. we now have 1 number, I didn't like the way it did the corrections, so I put her target to be 140-140 during the day and 180-180 during the night..works out well:)

[twodoor2]

Back to one of my original questions, if someone already answered it, I apologize. Lots to read in this thread!!

For the MM552 pump, can the IOB change from one minute to the next, if all other variables are the same (carb factor, carb grams, BG number, ISF). I'm wondering if the IOB is calculated off a smaller series of time increments than my formula which changes every half hour.

Thanks!!!!

[Twinklet]

That's pretty scary!! Does it warn you and tell you it's subtracting the IOB from the carb bolus if you do enter the BG? Can you even eat 10 carbs after eating ten minutes prior??? I thought that was a "no no" even in the world of the pump. I always wait three hours between all meals and snacks. If you're bolusing for 20 carbs and correcting at the same time, can you even eat another x amount of carbs a short while later? That's new to me. If the pump can do that, then why not with syringes??

With a pump, you can eat every 5 minutes throughout the day. I suppose you can also do that with a syringe, but that is a lot of shots. ;) There is no reason to wait a certain amount of time before eating. Simply bolus or inject for the amount of carbs eaten and then...eat! We are just manually doing what a fully functioning pancreas does.

We correct for a high and bolus for carbs eaten at the same time almost every day. If the correction factor and ICR are set correctly, problems are rare. The correction factor brings down the high and the ICR doses for carbs eaten.

We corrected and injected for carbs eaten at the same time when Emily was on MDI, too, but that is what we were taught to do.

Are you saying that if your child is high, you'd give a correction shot but there will be no food for 3 hours? :confused:

[twodoor2]

With a pump, you can eat every 5 minutes throughout the day. I suppose you can also do that with a syringe, but that is a lot of shots. ;) There is no reason to wait a certain amount of time before eating. Simply bolus or inject for the amount of carbs eaten and then...eat! We are just manually doing what a fully functioning pancreas does.

We correct for a high and bolus for carbs eaten at the same time almost every day. If the correction factor and ICR are set correctly, problems are rare. The correction factor brings down the high and the ICR doses for carbs eaten.

We corrected and injected for carbs eaten at the same time when Emily was on MDI, too, but that is what we were taught to do.

Are you saying that if your child is high, you'd give a correction shot but there will be no food for 3 hours? :confused:

I only give corrections with meals, unless it's at night and she's super high, and needs it during bedtime. I also wait at least 3 hours between all doses. I also don't give mid-afternoon or mid-morning snacks so that I can track patterns easily. She does get a bedtime snack and well proportioned meals, no complaints from her. Before the dx, she was a snacker, grazer, and she rarely ate her main meals. Now that there are no more snacks between breakfast, lunch and dinner, she eats everything, and she doesn't complain of hunger at all. My son is snacking at preschool, and now he doesn't want dinner. It's frustrating. My DD doesn't get a snack at preschool, so she's fine with her meals.

[Twinklet]

When Emily was on MDI, we were told to wait 3 hours for correction doses, but she could eat prior to that and get a shot to cover carbs. Ditto if she wanted 2nds on a meal--she'd simply get another shot.

[Momof4gr8kids]

I have a formula for IOB, but the number changes every half an hour. It seems the formula that the pump is using changes IOB every minute/second???

Let me just clarify, can you can have a different IOB one minute or every second? I have a degree in mathematics, and I wonder what formula the pump is using. It's just something I would really like to know. I can play with it our pump, and perhaps deduce the formula, but it would be nice to have it. I assume no one really knows the formula. The formula I have gives specific percentages of insulin left, but again, it only changes every half an hour. It also seems these formulas are different depending on the pump, and why???? Maybe they have their own proprietary formulas, and I'm sure it's based on the bell curve provided by the insulin manufacturer. I also wonder if the formula changes depending on what type of fast acting insulin is used since those bell curves are slightly different. Something I need to ask the pump educator about. I know, I know, probably more information than I need to know, but that's just me.

I'm sure because of this formula, the fact that the basal can be adjusted, and the precise units you can deliver with the pump, it's probably a better choice for insulin delivery if you want accuracy and you have greater insulin sensitivity. I'm just a number cruncher, and it always fascinates me how algorithms work, in this case, for the pump.
Ok, so assume Bob and Fred board a train to Delaware at 2pm EST. Both are pumping and can correct with 1/20th of a unit minimum. Bob and Fred both take 4 units and have an IOB time of 4 hours. Bob checks his bg 2 hours and 33 minutes later. His bg is 237. Bobs IOB left would round up because he is high to the closest 1/20th of a unit. It basically would be 1/20th of a unit for every 5 minutes. The dose has to be big enough, but yes it will change the IOB every minute, so if you check bg and it is 237, but wait 20 minutes to put the dose into the pump then you're going to possibley OD unless bg remained the same. That's why you are not supposed to correct using numbers from CGMS. Most doses are not big enough to make a difference by the second but if you are using a ton of insulin with a IOB of an hour, ect... then the second would have an impact....

On the other hand if you are using animas (not sure about other pumps) and are correcting a low your pump will subtract the IOB from the correction. So Fred has a bg of 40 and a target of 100. His ISF is 60 and his I:C is 1:10 So 10g of carb = 60 bg pts. Fred only has 10 minutes left of active insulin so that would be .1u. Fred ate 15g of carbs so the pump will subtract the .1u that is left on board as well as the carbs needed to bring bg up, but will dose for the rest. This helps prevent rebound highs from treating lows. It will also allow for bigger snacks and wont be such a big deal if all you could find is juices that are 20g ect... However when you have a high fat meal that will need insulin later and this is a low from having too much up front when the carbs have not digested yet, then you will either need to figure how much to bolus for later, or you will need to check and correct bg later. It's best to start correcting so that you have a better idea of the reaction time.

[funnygrl]

if you are 72 before you eat, and you go to bolus it WILL subtract from the amount of insulin it is going to give Kaylee...

for example

bg 72
carbs eaten 30
estimated total 1.4u
food was 1.7
correction was .3

it subtracted the .3 for correction

or

bg 81
carbs 30
estimated total 1.2
food would have been 1.5 but it subtracted .3 for its correction.

Sorry, I just reread your post and realized that you are talking about IOB.. for some reason I thought you were talking about subtracting from the carb bolus for a low blood sugar.. you are correct, it does not subtract for IOB... it'll only subtract from the carbs when you are below your target.. :)
It will lower the bolus for the carbs. Where it varies is with IOB. I didn't make this very clear, sorry.

For example,

BG: 60
Carbs: 45
Active Insulin: 1.0
Food: 3.0
Correction: -0.5
Total: 2.5

It won't subtract the IOB from the food amount. If you put those same figures in a Cozmo, it would recommend 0.5, because the IOB is subtracted from the total.

my edit: I just saw your edit and realized we agree, lol. I'll leave this up for clarification of the original post I made though.

[twodoor2]

When Emily was on MDI, we were told to wait 3 hours for correction doses, but she could eat prior to that and get a shot to cover carbs. Ditto if she wanted 2nds on a meal--she'd simply get another shot.

We were told the same exact thing, and that we could give snacks, and carbs whenever, but I find it's more difficult to track patterns that way. The snacks also cause spikes when there's already a spike from the prior meal, so like insulin stacking, I like to call this carb stacking.

To any newbies out there, if you can, I would highly recommend avoiding between-meal snacks as much as possible. It's really hard to adjust the carb ratios and other things when you have that. My daughter tends to spike after meals and then come down to target range, if you have a child like that, between meal snacks are a nightmare.

[Twinklet]

We were told the same exact thing, and that we could give snacks, and carbs whenever, but I find it's more difficult to track patterns that way. The snacks also cause spikes when there's already a spike from the prior meal, so like insulin stacking, I like to call this carb stacking.

To any newbies out there, if you can, I would highly recommend avoiding between-meal snacks as much as possible. It's really hard to adjust the carb ratios and other things when you have that. My daughter tends to spike after meals and then come down to target range, if you have a child like that, between meal snacks are a nightmare.

The thing is, we want our kids to live their life as normally as possible. I have never limited foods or prevented her from eating when she was hungry just because it hasn't been a certain number of hours. We were actually warned NOT to do that: That kind of stringent lifestyle, if continued, will create rebellion later. Your child should be able to eat snacks and still have an excellent A1C. We've been well below 7 for over a year now.

I understand wanting to detect patterns, but something you will learn is that patterns change rapidly with growth and it is something you will always be tweaking. Just when you think you have everything "just right", a change will happen, guaranteed!

If your daughter is spiking very high after meals, you may want to adjust the timing of your injection. Emily typically only spikes at breakfast, but that has been taken care of with a higher basal at that time and pre-bolusing by 30 minutes. If that doesn't work, her ICR may be off.

Of course, there will always be foods that cause each of our kids to skyrocket, but if spiking really high after each meal is common you might want to re-think your timing or ICR.