Just started back on Omnipod

So, I’m back on Omnipod for 2 days now. I’ve had bad numbers so far, first night kept climbing and ended up at 289. ugh! Now, I’m just high after meals, too. We upped my basal to .35 and we’re adjusting, as I realize this process from switching from MDI (which never worked for me and I had a low of 30’s 2 weeks ago with paramedics having to be called) to a pump takes time and is not a panacea.

My issues is with the way the PDM calculates IOB, target range and ISF. I’m not understanding that if I do a correction 1 hour before lunch, then need to bolus for lunch, all these programs take away my full meal bolus to cover the food because it’s deducting insulin from the 1 hour prior correction. How does all this work? What do most people have as insulin duration, target range, etc… Seems I’m just trying to guess with a pump the same way I did with MDI. I love not having to give injections and I know I’ve just started out on this but is the pump that much better? I’m not sure I have a choice because any type of real exercise just drops me terribly.


It’s arguable, as John Walsh has done in the article linked below, that a lot of people use a value for their insulin duration which is too low. I have never really done a thorough test of mine and I wonder if anyone else has bothered or if we all just think “we know”. I also wonder to what extent DIA varies with time of day and activity.
"An Accurate DIA Prevents Excessive Insulin Stacking" by John Walsh and Ruth Roberts

My belief is that my DIA is probably around 4 1/2 hours. Of course, my pump only accepts an integer value so I have to pick either 4 hours or 5 hours. Arrgh. :angry:

It occurs to me as I write this that I should probably just try to parallel my pump’s suggestions with those from a more finicky bolus calculator if I can find one. Possibly as an iPad app? Hmmm …

Thanks. I have my duration set for 4 hours. I honestly hate this…ugh! starting back on pump because I feel like I have no control and/or don’t know what the heck I’m doing, because I don’t. All the settings have to work together for it to be effective. patience, patience, patience. thanks!

I think most people use 4 hours. Setting it at less than 4 hours without having actually tested to verify that your body metabolises insulin that quickly will, as Walsh argues, throw off your other settings.

Of course, if you follow pretty much the same routine every day then you will probably get your pump settings to harmonize for you. But if the assumptions are wrong then when you vary the routine things will go bad in one direction or the other.

I think what also throws a monkey wrench into DIA calculations is variability in insulin absorption. I actually don’t recall anyone ever trying to factor that into the problem of determining a more accurate DIA. :frowning:

Hi, Sarah.

My son started pumping just a few months after being diagnosed - nearly nine years ago - and I still remember how frustrating, and for me, scary that time was. Everything I knew was no longer relevant. Numbers were just not making sense. Adjustments made by the doctor were not working. We did eventually adjust and life was much easier for my son on the pump, but the transition was difficult for us.

I may not be understanding your issue/question correctly, but it sounds like you corrected an out of range blood sugar and then wanted to bolus for a meal an hour later and ended up high after that meal. It sounds like you attribute this to the reduction in meal bolus calculated for the correction IOB that existed when you ate.

If I have that correct, I would ask if you had a new glucose reading at the time of your meal. If you did, then a calculation would be included that recalculates how much correction insulin you need based upon your new BG and a calculation for the meal bolus. If that calculation was done, presumably, the IOB calculation would not be the cause of your high BG.

If you did not have a new BG, theoretically, you should/could assume that the correction bolus was appropriate and needed, and now you need a full bolus for food and should not reduce your meal bolus for IOB - the IOB is assumed as needed for the blood sugar it corrected and hour ago.

So on the topic of duration, at the risk of being highly scrutinized, I will share that my son’s is set for 2 hours. I am not recommending that anyone else do the same, but this is what we do for mathematical calculations that always include a review and manual adjustment on our part as we see fit. We’ve had it at 2 hours ever since he started pumping, and he is an Apidra user. We do this to avoid the erroneous reduction in IOB that we saw with a longer DIA that resulted in highs, but we know that there is a tail of insulin that makes actual DIA longer than the programmed 2 hours. I know people will read that and say - well that’s just stupid - if you know it’s longer then make it longer. The mathematical calculations with a longer duration just did not work for us. When we were trained, our CDE prescribed the 2 hr duration. The trainer made it 3 hrs. The CDE changed it back. So clearly, there are differing opinions and strategies.

As you have pointed out, there are so many settings to determine and it’s really an evil exercise to try and figure them all out at once. There are simply too many variables working at once and it’s hard to identify which needs to be tweaked with none of them being “known” out of the gate.

Back to DIA, what is unfortunate about the way OmniPod, and I think most other pumps, calculate IOB, is the fact that it’s determined by a straight line method. The bolus amount is divided by the number of hours in the DIA and that’s the amount that is attributed to each hour. In fact, insulin does not work that way. If DIA is truly 4 hours - let’s just say that for argument’s sake - more than half of the effectiveness of a bolus takes place in the first 2 hours, but the pump calculates it as only half. That means it attributes half of the insulin to the second two hour period, when in fact the tail of DIA is less than that during that period. Insulin just does not work in a straight line way. The cosmo pump, which is no longer available, used a more sophisticated calculation for IOB that better matched actual DIA. If the OmniPod used that method of calculation, Caleb’s DIA would be set as longer.

So, where does that leave you? Probably no less anxious and frustrated, but maybe with a little better understanding of what the pump is doing. We took copious notes when Caleb first started pumping and that really helped us to isolate causes and make adjustments. I think you are right, it just takes some time and patience, and eventually things will be a bit more refined and much easier, although we are continually refining even after eight plus years of pumping.

Yeah, something like that. But as long as you remain aware of it and take it into consideration as a possible factor when things go wonky … I personally am more concerned about the folks who unwittingly set a low DIA, forget about it, and then later are puzzled that when they do what their pump tells them to they are plagued by hypos caused by the insulin stacking resulting from the pump’s “bolus calculator” relying on an incorrect assumption.

The thing is, the DIA is something which, in theory, is easy enough to validate especially for those who use a CGM. You make a correction and then keep things relatively constant and wait to see what happens. If the BG pretty much always drops to the target range and then stays constant/flat, then I’d consider the settings correct.

If, on the other hand, this never happens, then the settings are not a close enough match to the physiology they are trying to predict. I would suggest trying to cautiously tweak at that point. In particular, if the BG drops until the DIA is zero and then continues to drop, either the DIA or the basal rate would appear to be wrong.

Of course the catch in the above is that it’s easy to keep things relatively constant while waiting to see what happens after a correction. I never seem to want to do that … :confounded: :smirk: I expect it would be even harder to do in the context of the full, active life your son seems to lead, Lorraine.

But I would still urge that you try to periodically sanity check your son’s DIA. As he ages it could well change from whatever it may have previously been.

Quoting from the Walsh article I referenced earlier …

###Linear Versus Curvilinear DIA Measurements
A BC [Bolus Calculator] measures residual bolus insulin activity either linearly (ie, 20% per hour for a 5 hour DIA) or curvilinearly. The curvilinear method more closely approximates insulin’s delayed onset of action and its gradual tailing off of residual insulin activity. Realistic DIA times for today’s insulins range from 4.5 to 5.5 hours for BCs like the Insulet patch pump that use a linear approach, while DIA times of 5 to 6 hours are more appropriate for curvilinear systems that include insulin’s tailing activity like the Animas and Medtronic pumps.

As I’ve said, in my case with my Medtronic pump I feel 5 hours for DIA is too long. I just don’t think I see any further BG reduction somewhere towards the end of that period. But I’ve never been sure whether what I’m seeing is a result of the insulin being metabolized in less time or that site absorbtion problems resulted in a smaller bolus than my pump is assuming. I’m not really sure how to figure that out either.

Ooo - I didn’t realize Animas and Medtronic did it that way. The edition of Pumping Insulin that I have is from back when Caleb was diagnosed and includes the cosmo pump. Any idea what the formula is that’s used for those curvilinear calculations, @irrational_John? That’s a big plus, in my opinion.

Unfortunately, no. I wish I did, but I’m not sure how to track it down. I think it’s known well enough to those who work on the software for the bolus wizards, but I’m not sure how to Google search for that. :wink:

To make things a little more disappointing, I am not sure that my Medtronic uses the equation, at least not directly. I read in one of the claims by another bolus wizard product that the pumps use a table lookup scheme rather than calculating the active insulin value directly. That seems somewhat likely to me as it would explain why Medtronic still only allows specifying the DIA in terms of hours. (You can’t specify 4.5 hours, only 4 hours or 5 hours).

Doing it via a table lookup might have made sense back for earlier model pumps when there were more constraints on the hardware. But to keep doing it that way now is absurd. But as long as they don’t feel any pressure to change it, Medtronic probably will just leave it as it is rather than expend the resources to do it (somewhat) more correctly. <sigh/> :disappointed:

I think it’s the calculus integral function. I’m not conversant in its use but I know it’s non-linear. And I think that the various pump brands tweak their software function to its own special magic sauce.

For what it’s worth, I’ve set my duration of insulin action to 5 hours after many unexplained lows 3-5 hours after a meal bolus dose. My IOB would indicate zero and I was fairly confident that my basal was pretty close. After making that adjustment, I had fewer unexplained lows in that circumstance.

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I don’t have Omnipod, but have used MM for almost 20 years.
I have my pump set to 3 hours for DIA. (if MM allowed it, I would probably change to 3.5)

However, I never use the bolus wizard to calculate insulin dosage for me, but do check the status screen to check IOB as I make my own calculation for a given situation.
When I see the pump’s IOB, I also mentally try to guess my current ‘Food on board’, and usually come to the conclusion they will cancel each other out.

I think the ‘actual’ IOB for me is 4-5 hours, but I also know most of my meals and snacks contain more fat/protein than the traditionally recommended ADA diets. So my opinion is that even though I may still have small amount of insulin during hours 3-5, I also have fat/protein that is still digesting. I have had T1D for many years, so my digestion system is also on the slow side, even with carbs. The pump calculations don’t take factors like these into account. Your situation may be much different.

Also, since I have Dexcom CGMS, should I start to drop too low 3-4 hours after a bolus, I can easily see that, and correct with a small snack, often a nice treat !
Before Dexcom, I used MM CGMS, and did try using the bolus wizard. But felt it was too simplistic to only take into account BG, carbs and IOB. I knew much more about food on board, activity level, illness, stress, etc.

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There are so many factors to consider. I probably would change my I:C ratio or basal rate in that case. Glad your change of DOA worked for you.

Thanks so much for your reply and to everyone. So, we increased my basal to .40 and my ICR too. I cannot get me BG’s below 220. I woke up every two hours last night and gave a correction and it won’t come down. I’m close to 250’s yesterday after meals. What does this mean, I changed my POD yesterday, can it be a bad site. Here’s the thing, I am a very petite, tiny woman with not a lot of fat. My pump nurse was a bit concerned as these seem a bit bulky for me but, as Lorraine stated, kids wear these. I can’t take these highs. I took the POD off and am going to do injections today and try it again tomorrow. It seems like I am taking a heck of a lot of insulin and stacking all over the place, not using any of the calculations set in the POD, I’m just guessing which is what causes trouble for me on MDI. Any insight would be great.


If you’re just winging it all the time, what’s the point of trying to give advice?

What you seem to need to do is to take a breath and back away a bit instead of constantly reacting. If you can’t do that, then yes, I would expect you to be ping ponging all over the place. At least that’s what has happened with me in the past.

I was asking if it sounds like my site is bad if i’m correcting and my blood sugars are not coming down and I increased my basal rate to .45 and still nothing, which is a lot of insulin for me

I just took off my pod for now, took 4.5 units levemir and 1 unit shot of novolog and am dropping and will eat. so, it seems something had to be off with my POD or site, no?

I think I would consider a different approach.

  1. Scar tissue?? Are you placing the Pod in the same place(s) that you frequently administer shots on MDI? Consider trying to find a spot that’s away from your frequently used areas. Like you, I’m pretty thin (but not petite, lol!), so real estate can be a bit challenging, I know.
  2. Consider giving yourself an intramuscular (IM) shot (after consulting with your doc, of course) to bring down a high, after moving your Pod to a different site.
  3. Use a fresh vial of insulin to fill your new Pod. Actually, if you do an IM shot, you should also use fresh insulin.

I typically walk through a little mental checklist when my BGs are running higher than I would expect.

  1. Different food (high fat, high protein)? There might be delayed/longer period of high BG.
  2. Lowered activity? I might need a higher basal rate along with a slightly higher correction factor.
  3. Bad infusion site/low absorption due to scar tissue? If 1 and 2 don’t apply, move it!
  4. Bad insulin? If I have changed the infusion location, and I am still not seeing my BGs coming down, I will sometimes try an IM shot into my forearm muscle. Normally, though I would just change out the insulin in my pump for fresh and see if that has a positive effect. Of course, I am on a tubed pump, so my insulin is in the cartridge much longer than the 3 days you get from a Pod.

For me, yes, the pump is dramatically better than MDI. At the same time, I still do a lot of calculation in my head so that I can check and correct what my bolus calculator is telling me. I pumped for a long time without a BC, so it’s kind of second nature for me. Like @Lorraine mentioned, I have a great dislike, okay, okay, I despise the flat-line IOB calculation, so I frequently have to add/subtract from the recommended BC dosage.

Exercise is a whole different animal, but IMO so much more doable on the pump because you can use a TBR, lowering your basal 1 - 2 hours before your activity and depending on the exercise, running a bit higher BG than you would tolerate in your non-exercise state.

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we have to constantly react, that’s part of our job as type 1’s. if my blood sugars don’t come down, i’m correcting with the POD - PDM all day and night, something is wrong. If I take an actual shot and my blood sugars drop, then…I have to react. I (we) are just winging it right now, that’s what the transition from MDI to a pump is, trying and then retrying and trying again. I (we) really don’t have a starting point because MDI never worked for me. thanks!

The change of insulin duration uncovered a need to change my insulin to carb ratio.

Yes, but you need to think things through before you act. You don’t seem to doing that. You seem to be panicking and throwing insulin at the problem without pausing to take into consideration how your previous actions should inform your current ones. i.e. Stacking.

If I’m wrong, I’m wrong. But that’s the impression I am getting from your posts.

My approach to a bad site is possibly a little more direct than YogaO’s. I give the bolus time to take effect. If a correction doesn’t seem to be taking hold I may try another. If, after waiting a two or three hours, a second correction does not “take” then I’ll inject. If the injection has an effect whereas the pump bolus did not, I’ll try another site.

The above is if the high BG seems stable. If instead the BG seems to be increasing at a relatively rapid rate I’ll skip the wait and inject a correction bolus. But I haven’t really had that happen very often. My worst recent experience was when my BGs got into the 500s because I didn’t reconnect my pump (tubing) correctly. That was unpleasant, but after I sorted out the problem it started to correct.

I would only consider futzing around with my insulin source if I had some other factor to make me doubt it’s efficacy such as it was accidentally exposed to (very) high temperatures. Reasonably well cared for insulin has never gone bad at least in my personal experience. Problems with stubborn high BGs have pretty much always been a result of a bad site. Possibly a few times they resulted from an illness, but it was long enough ago that I no longer have a clear memories of it.

I think it is less likely a site issue than a matter of adjusting to pump therapy.

Your situation makes me think of some things we experienced when Caleb started pumping:

  1. Caleb was using NPH and Novolog before pumping. The NPH stayed in his system for more than 48 hours. Even though we were viewing NPH to have a duration of 12 hours, it was impacting his blood sugar for much longer than that. When it finally cleared, we had a clean slate with which to work to figure out his proper settings with only Novolog. If you reintroduce a long lasting insulin while trying to figure out pump settings, I fear it will complicate your ability to properly determine your settings.
  2. Caleb had a TDD of less than 2 units of insulin when he started pumping. This was an issue. As I noted, when he started pumping, the NPH was still working and we were about to begin using diluted insulin because we could not set the pump settings low enough with undiluted insulin. However, once the long lasting cleared, his insulin use more than doubled. So if his endo determined that he needed 1 unit of basal throughout a 24 hour period because that’s the amount of NPH he was taking, we found he actually needed closer to 2 units with just Novolog. NPH units did not convert on a 1:1 basis to Novolog units.

Another issue we had was Caleb’s overnight numbers. I was fighting non-correcting 300+s night after night and the doctor would only recommend the slightest adjustment in his basal settings which did absolutely nothing. It was brutal. I was still new to diabetes and we had never seen 300s on injections and I was certain I was going to end up in the hospital with him. Every two hours I would correct and the numbers wouldn’t move for hours, although I was able to get him in range by 3 am or so. With experience, I came to believe this was a time of day that Caleb was growing and he just needed substantially more insulin during that time than any other part of the day. This was another area where NPH seems to act like a sponge and soak up that irregularity. I just truly believe that the power of a long lasting insulin is very different than a fast acting one. The bumps come more often and more erratically, but you are also able to address them more nimbly.

If you are having highs that you can’t correct, your IC ratio is off or your basal is off or both. I find starting with upping the basal helps address the cause more easily. The adjustment you made may not have been enough even though it may seem like a lot.

I have found that it is almost never ever a delivery issue with the Pod. We had more delivery issues with the original system, but since the smaller Pods were introduced, the incidence is close to zero.