IOB - Target Ranges - Corrections with Omnipod

OK, have a few questions please.

I thought I'd bolus for coffee this morning at 10am, small bolus .45
at lunch I was 77 (maybe I bit low but I also did a short, small workout)...I bolused for lunch and ate the same thing as I did yesterday 30 carbs - Pod gave me 3.05 units yesterday - i had no spike and was 86 after lunch. Today,however, with the same lunch - 30 carbs, it gave me 2.30 units. So, it's still calculating that small .45 bolus 2.5 hours ago and does it also take off insulin because I'm 77? So, how does this work, how will this 2.30 units cover my lunch when I really need 3 units? My insulin duration we changed to 3.5 on Tuesday.

Hope that makes sense. BTW, I frickin LOVE the Omnipod, hope I never have to go back to injections and levemir again. :)


I have a Ping Sarah, which has a different system, but with the same principal: If I'm on the low side and the Ping takes off for that number when I go to bolus for my meal whether it's due to IOB or not, I still bolus the full meal carb. I've found from experience that if I don't I will go high. If I'm lower (60s) I will bolus and eat right away rather than pre-bolus. If I'm lower than that I will either treat first and wait to come up or else eat without bolusing and then check after my meal for when I come up into normal range, then go ahead and bolus for the meal. That's what I've found works for me.

You should have a target BG programmed in.

Based on your starting BG and amount of carbs you eat, your pod will calculate the amount of insulin needed to cover your meal and bring you back to your target BG. If you start with a low BG, or IOB, your pod will subtract insulin from your bolus to bring you back to your target. If you have an elevated BG, your pod will add insulin to your bolus to bring you back to your target. Insulin duration will affect your IOB. Your carb ratio will also affect your bolus calculation so if you have multiple ratios programmed in, your bolus will not necessarily be the same for the same amount of carbs if you're eating at a different time.

Hope this helps!

OK, so do you override the calculation your pump suggests? Not sure if it's the same thing for the Ping? So, I would just manually enter 3.05 (which is what the POD calculated and gave me yesterday). Isn't that one of the reasons why we use the pump, because it's supposed to factor in - calculate all this IOB stuff..but again, just don't see how 2.3 is going to cover if I need 3.0 units. Do you ever use the IOB feature? Thanks, Zoe.

Sarah, your PDM is, indeed, calculating your bolus based on a number of different factors, any of which might be different from yesterday. A lower BG premeal, or IOB, or different IC ratio because you are eating at a different time, among other things, could give you a different bolus calculation even though you are eating the same number of carbs.

Sometimes I will add or subtract insulin for things the pod does not take into account, such as pre or post exercise conditions which will definitely affect my IC ratio temporarily. But, unless I have a reason to second guess the calculated bolus, I let the pod do it's thing.

OK, thanks. Yes, pump nurse set the reverse correction. so pod subtracted .90 units from bolus for correction because I was at 77 and then deducted .10 for insulin on board. Still don't see how this, realistically, works. If I need 3 units for 30 carbs, I need 3 units not 2.30 units. Do you use what the pump calculates, don't you go high?


Yes, I ignore the calculation and bolus for the full carb bolus. On the Ping you always have to manually enter the correct amount. Also if you want you can just ignore "add bg" altogether and just go with the carb bolus which I do usually unless I'm high.

Yes, I pay attention to the IOB feature always when doing corrections for highs. It makes it so much easier than with MDI!

Yes, we use smart pumps because it calculates things but we are all different and so we both set our pumps for what we learn works for us and also make decisions sometimes to do something other than what it recommends based on our experience.

Np Sarah.

When you say "I need 3 units for 30 carbs", your PDM needs to have a target BG to shoot for in order to determine that 30 carbs requires 3 units, and a reference point to start from. So, really, it's "I need 3 units for 30 carbs to get me back down to X BG if I'm starting with a BG between Y and Z". If you raise your target BG, your PDM will compensate by lowering your bolus amount for the same 30 carbs. At the same time, if you are starting with a lower BG, your PDM will also accommodate and readjust the 3 units to account for the fact that your BG will not rise as high due to the same 30 gr of carbs.

If you get a chance and haven't done so, take a look at your Settings > System Setup > Bolus/basal/calcs. That will have a lot of the information that your pPDM uses to calculate dosing.

yeah, that's where i looked FHS, that's how it calculated it; the deductions I mentioned. I'll see where my BG is in two hours....thanks. LOVE MY POD! So happy, ha!

I DO see a potential logic hole here. The PDM knows about IOB. Does it know about FOB? Since the two work to balance each other, accounting for one but not the other could definitely tilt the answer, seems to me.


well, because it's factoring in (and deducting) IOB of a .45 unit of insulin I gave 2.5 hours before my lunch bolus, which, because it's such a small amount, probably would burn off within an hour. So, trial and error. It's only a machine, I'm the brain behind it, i suppose. :)

Remember, that all of the insulin will not "burn off in an hour". Fast acting insulin is in your system for about 3 to 4 hours. So even though it's just a little bit, a percentage is still active hours later. The pump uses an algorithm to determine how much is in your body at anytime. That's why your settings need to be accurate and not telling the pdm how many actual carbs you eat can be dangerous. It is "only a machine", but it's a pretty smart one :)

Now, if later on you are higher than you want to be, your setting may be off and need to be tweaked (changing the target, changing the insulin duration, I:C ratios, basals, etc.).

Well, I, of course, was higher and had to go ahead and add back the bolus amount the pump deducted anyway. just spoke with my pump nurse, we took off the POD reverse calculation and added another basal rate from 2 - 7pm of .05 when I usually start to go higher. We'll see. .45 units isn't going to do anything after 2.5 hours, not with me anyway. it's less then 1/2 a unit.

I know what you're saying, Sarah, but the issue is with stacking insulin. A bit here and a bit there (which is oh so easy to do with a pump when you just click a button instead of pulling out the ole syringe) adds up. This is why accurate settings are important and why I mess up when I try to overthink it :)

Then again, I may be more sensitive to insulin than you. A half unit will move me about 25 mg/dL (meaning .05 should move me about 2.5 mg/dL). It's always a moving target :)

yeah, 1/2 unit will correct me down about 25 points...i'm very careful and insulin sensitive too. I understand IOB but not 2.5 hours prior with .50 on board, the Omnipod doesn't factor in the amount of insulin on board vs. the time it stays in the system, i.e. 2 units IOB given 2.5 hours prior is different then .50 unit given 2.5 hours prior. The pump does need a brain, too..ha!

I thought of one more thing, Sarah :) I know you have the new system (and I'm still on the older one) so I don't know *for sure* that it's the same, but on the old system there is a "?" on the right button. Before I confirm a bolus I can hit the button and it tells me exactly how it got to the number it wants to bolus. Maybe that could help solve your mystery? Good luck!

thanks, kate. yeah, I have that feature too. Pump took off too much for my BG of 77 (reverse correct) and too much for .45 bolus given 2.5 hours prior. My pump nurse suggested turning off reverse correct, which we did. I don't consider 77 low or need to be corrected before. If i'm truly 'low' before I eat, i'll eat first, bring up BG's then bolus for meal.

Have to change my first pod in about an hour...kinda nervous, wish me luck..ha! Much easier process with POD compared to tubed pumps. Should be fine. THANKS!

well, so much for the POD....I changed my POD yesterday, there was a bit of a rash, used the Barrier Wipes for the new POD, by end of day felt like my skin was on fire...also, again, way too much basal, 10:30 at night, couldn't keep blood sugars up, dropping, dropping, weekend, no one to ask..ugh! Took my pod off and the entire site looks like it's been burned with a rashed rash. Can't use this pod, even the barrier wipe isn't working. Horrible, night..I changed my CGM yesterday too, someone mentioned good place was outer thigh, which I did, saving my tummy for PODS. CGM was messed up all day, 2:30am....beeping, blasting, double arrows down, low, low, checked meter, 127, recalibrated, low, low...then just LOW AND A LOUD BEEP...SAYING 39. Changed CGM at 3:30AM been up ever since. Blood sugars high 190's because going back to MDIs. Trying humalog. I'm so burned out on this. I feel awful. Maybe the MM revel will work, smaller, different infusion sites. BG's all messed up from again going from MDI to pump back to MDI...I wish this would stop sometimes, ya know. Thanks for listening.

Sorry you're having such a hard time, Sarah. It seems you are learning so many new things at once any one of which can be super frustrating. I don't know a darn thing about pods but I know it really took me awhile before I got things going smoothly with my Ping. Hang in there. Remember to only change one variable at a time so you can see what is working and what isn't.

Just want to add that pumping is different than shots. You can’t always assume that past numbers will work for you although it’s a place to start for settings. When I switched from Medtronic to Animas I even had to lower my basal rates by 10% and my numbers used for bolus calculations changed a little too.

I find it much easier to see what’s going on with my blood sugars if I take a few days and don’t override the bolus calculations. I would much rather work with the settings in the pump the majority of the time vs override frequently. There’s a lot of times it’s appropriate to override but I find if I do it too much it makes it a lot harder to figure out what’s wrong when something needs changing. I can never remember later why I changed the bolus or ran a temp basal if it’s been a few days.

Sorry about the rash. I reacted the same to a demo pod so I could never switch to Omnipod. I don’t have any trouble with other infusion sets though.