You know, I can’t figure out how C-IQ does IOB. If I do a correction like .5 to 1u IOB doesn’t appear very long, certainly not more than 2 hours.
It may be that it is somehow related to basal rate which can drop to zero.
It does appear that my bolus dropped 50% in an hour an a quarter. I just looked at 8:36 and zero IOB, that’s 3.5 hours. 
I suspect that it is calculated as the total amount of insulin injected minus the total amount adsorped minus basal required. Hum:
IOB = (Σ(insulin injected) - Σ(total insulin adsorped)) - Σ(basal required)
With some built in decay so that past discrepancies disappear. The insulin model determines “total insulin adsorped” and the correctness of that model is the first thing that messes things up, or makes them right. The problem with the equation is that “basal required” is also needs to be subjected to the insulin model; if it was required an hour ago then by now it is just high BG, so missing basal gets converted to high BG, raising insulin-injected and excess basal goes to low BG, etc.
That’s why I don’t like the subtraction, but without the subtraction at 0 IOB we would be dead. It’s probably discussed to death somewhere on the Loop devs mailing lists.
I do not, but I’ll take a look!! 
Omnipod (original and Dash). I’d usually stop insulin delivery 1-2hrs pre workout, and IOB was very clear.
Susan,
I measure my Bosal very accurately. On any day that I don’t have any anaerobic or aerobic activity I take 15 units of Humalog, my Bosal insulin. On the days that I have anaerobic and aerobic workouts I cut that down to about 12 units. I try to keep my BG around 120 before any exercise. During my exercises I watch my BG gradient to may sure I don’t have a large negative gradient to make sure I don’t have a low before my planned exercise termination. I have determined that when I run, I have a positive BG gradient. When I walk or have an anaerobic workout, I have a negative gradient.
Yes, I watch very closely my carbs.
I have been a T1D for 48 years. I have been successful to keep my A1C around 5.3.
I can give credit to the Dexcom system, but a very important element is my monitoring system. I use a standalone watch that links to my phone when it is in range.
Calibration of the Dexcom is very important. I usually check the calibration at least 4 and sometimes 6 times a day. The sensor accuracy is very location dependent.
Obviously, I don’t use a pump but muti-daily injections.
Dennis
You knew how to do it back on the Omnipod, so maybe go back to that technique for exercise. Turn off Control-IQ 1-2 hours pre workout, set a temp basal of 0 for, what, 3 hours? And keep an eye on the CGM to see if you need to tell the pump to give you any manual corrections.
I’m trying things like that, the difference being that control IQ has been doing its thing all day, so when I read IOB on my Tandem (shows what’s left), it’s different than IOB on my Omnipod (shows my whole day of extra insulin). Even though the extra shouldn’t be “on board” I ALWAYS go low if I’ve given extra during the day, even if it’s the morning.
Another thing I have SUCH a hard time with is communicating this to my Endo. He’ll say “well, the data doesn’t show this low…” IT’S BECAUSE I SAT THERE STUFFING MY FACE WITH 30 GLUCOSE TABLETS. It’s so frustrating, because no, it wont show the low, but that’s only because I prevented what would have been a terrible low. I tried making my own charts of data (manually documenting these experiences), but even though my Endo is gold, he’s not going to go through my notebooks, he’s going to at most look at my graphs via Dexcom Clarity, which DOESN’T SHOW THE LOW.
Therefore, I can’t seem to figure it out, nor get help. And, sometimes the same activity, same time of day, same circumstances will have a totally different result. If I plan an exercise like an after work bike ride, I usually have to turn off control IQ for the day, do no boluses, eat only protein or very low carb stuff like raw veg (non-starchy variety), then put on the lowest basal (0.10 per hour) one or so hours pre workout, then do the workout (ie the long, strenuous bike ride), and whilst riding drink juice mixed with water. This is the only way I’ve been able to have no low, but then I’ve had some highs AND it’s SOOOOOO much sacrifice to do a bike ride that I’m depressed and just don’t find it worth it.
I’ve been on my pod since yesterday morning, and although my numbers haven’t been as good, I’ve had not ONE low, and it was so nice to just SUP board yesterday without worry of the tandem getting wet, without worry of a low, jump in the ocean, swim around, etc. YET, I had normal blood sugars, then a VERY high (17.9) was in the 12 range a lot of the day, etc. Not ideal for long term or at all really.
Do you mean bolus, or basal? If you are MDI, wouldn’t Humalog be used for your bolus based on food intake? Or are you really taking Humalog as a basal insulin, much like pump users? Just curious as it sounds like whatever you take, it is definitely working great for you!
That sometimes happens with delayed absorption if the cannula is in a place that has been overused (the “scar tissue” problem.) To test if that’s it, try placing the infusion set somewhere that you haven’t used before. One advantage I experience from a tubed pump is that the sets can go in lots of places that are unsuitable for a pod because the pod sticks out too far and hurts if pressed on. For instance, I can wear infusion sets on my back and lean back in a chair without noticing the set at all, but I can’t tolerate that with a pod.
Yes, I meant Basal for my Humalog and the old time NPH for my Bolus. I’m not sure that diabetics realize there are a cople types of insulin that don’t require a prescription. One of them is NPH. It is also very inexpensive.
Obviously, Humalog does require a prescription as does all fast-acting insulins.
I like your very familiar xDrip watch display.
Thanks! It was VERY familiar yo me, too, at one time!!
I’m using iPhone and Loop now though.
I think there are tons of strategies you can rely on to reduce how much extra food you have to nosh on to prevent lows but I think you’ll probably have to take in some extra carbs. I think one thing you can do is make sure you have no insulin on board heading into your exercise, so unplug/zero basal at least an hour before the exercise and/or time your meals so that you have no leftover insulin from the past one, and then plug back in with a zero basal on the bike ride, so you can give yourself some insulin if needed.
One thing to look out for – you can still get large amounts of ketones even if you’re at a perfect blood sugar if you’re going without insulin for several hours. Your muscles may be taking in so much glucose from the blood stream that your blood sugar stays at 80 – but your kidneys and many other internal organs will still need a baseline amount of insulin to operate and below that they will generate ketones to produce energy. So you can’t really drop your insulin levels SO LOW that you get no food or insulin for hours and hours. Which is sort of a bummer as most people rely on exercise to help lose weight. I think it’s trickier with T1 for sure.
I know I’ve overused my stomach for soooooo many years. I’ll try that. I thought the Tandem would bring new sites, but every time I try my legs I rip it out. My back is for my Dexcom, but I could try it out. That delayed absorption makes a lot of sense since my norm is high high high then crash low low low never steady (pod). Better on the Tandem, except when exercise comes into the mix.
Just a somewhat minor correction here, but of interest since we all analyze insulin needs as it relates our physiology…
But our kidneys do not need insulin for glucose uptake!
Insulin uses glucose transporter type 4 (GLUT4). There are 7 organs/tissues that do not require insulin for glucose uptake. They use different transport types for glucose uptake.
The organs/tissues that do not require insulin for glucose uptake are - the brain, red-blood cells, your intestine, cornea, your kidneys, your liver, and exercising muscle.
While this may seem confusing, it makes sense if you think about it. For example, if your intestine used insulin for its uptake, none of the rest of the body would ever get any glucose. It would hog it all, because glucose arrives in the intestine first.
Our brain uses more glucose than any of the other organs in the body! If our brain needed insulin, we would die without insulin much quicker. (While many tissues can also use fats and protein as an energy source, the brain and red-blood cells can only use glucose!)
While all of this might seem hard to remember, there is an easy way to impress your friends at the next cocktail party because you have it memorized.
The mnemonic device for this is “BRICKLE”
B - brain
R - red-blood cells
I - intestine
C - cornea
K - kidneys
L - liver
E - exercising muscle
(It is only exercising muscle. Muscle at rest does require insulin.)
I am still using the Sony SWR50. It has been perfectly reliable for all versions of the Dexcom G5 and G6 transmitter data as well as displaying all of the cards from my phone when in range. The transflective display is hard to beat.
I agree! I’d still be using mine if I had not moved to iPhone/iWatch for Loop!
Thanks for that correction! I guess it makes sense that organs which are awash in glucose all the time would be less likely to need insulin receptors to make use of it.
The curious thing about this is that it doesn’t quite work.
If it were the case that the liver relied solely on GLUT2, or any transport that doesn’t not use insulin, the liver would react to high BG in T1Ds by sucking up the glucose; no insulin required. And if the response was controlled by glucagon that would work in non-T1s but in T1s glucagon production is unregulated and the liver would simply dump all it’s glycogen (as glucose) then stop.
When we inject insulin somehow we manage to cause the liver to take up glucose; it’s the only treatment most of us take and injected insulin has no effect on the alpha cells.
So far as I can see liver function has to depend on GLUT4 as well as GLUT2. Otherwise I don’t see why we need such a big basal insulin dose.