I used the Tandem T:Slim with Control IQ. The pump does not really work for rises in BG because of DP or FOTF. As an example this morning my BG was up to 120mg/dl. I requested a bolus and the suggested based on my CF was 0.5u. I know this was not enough from my past history and so I did a bolus of 1.5u.
I am curious as to how well other pump algorithms deal with DP and FOTF, especially the OM 5 and open loop systems. I am happy with my pump and have no problem overriding the suggested bolus if necessary.
I think you’re doing it right. The algorithms have to use conservative insulin dosing because if they give too much they have no way to recover, so their need to be safe means we either go high or take more insulin than the algorithm would dare to give us (because we have glucose tabs at the ready in case we take too much.)
The deeper issue is that biological BG regulation is a complex system in control theory terms; it’s impossible for an algorithm to accurately model the future effect of an insulin dose. They can model an expected outcome, but it frequently will be wrong, sometimes by a lot. I enjoyed Dan Heller’s discussion of this in Why AID Algorithms Don’t Improve: The Category Error
Bottom line is that BG management has too many interacting factors that influence each other, it’s not a simple machine where if you push exactly this hard, it will move exactly that far. Think of a beginner driver, who thinks that if they hold the steering wheel straight, the car will go straight. They quickly learn to make continuous small adjustments to the steering wheel based on where the car is actually going. Managing BG is like that.
With O5 I started out with the same target all night. I could then see what time DP generally kicked in, and dropped my target (for a more aggressive adaptive basal) beginning an hour before that. It works really well at keeping my trendline steady.
I have the opposite of FOTF. I drop as soon as I get out of bed. I don’t think any regimen is going to manage that.
I use a hybrid closed loop system, DIY Loop. It’s called “hybrid” since it relies on the user to manually input meal nutrition and therefore meal bolus insulin. The version of Loop that I use varies the basal insulin amounts as often as every five minutes to affect the programmed BG targets. I’m aware of an alternate algorithm that uses “micro-boluses” to affect BG levels.
I have observed, for many years, both dawn phenomena and “feet on the floor” morning glucose rises that usually exceed the ability of algorithm to keep my glucose below 120 (6.7). This is my personal allowance for BG rise caused by DP & FOTF. I suspect that in a healthy non-diabetic this threshold is < 100 (5.6).
Here is today’s Tidepool graph which represents a typical morning for me.
Today, like too many other days, I woke up at 1:46 am and saw a 111 BG on my phone. I took 0.3 units of insulin since I target overnight BGs at < 100. I woke up at 6:30 at 86 mg/dL and my DP/FOTF rise started about 30 minutes later. You can see the Loop DIY algorithm already taking significant basal action (the bottom trace above) but from experience I knew that this effort needed support, so I delivered 0.5 units at 7:39.
At 9:00 am my BG is 92, right where I want it. If I hadn’t delivered that last 0.5 unit bolus, it probably would have resulted in a 9 am BG of 120 or more.
This morning is typical but not always. I still live with T1D, wild cards are still present and make themselves known. When that happens, I make adjustments. The sooner the better. My list of adjustments when this tactic doesn’t cooperate? Delaying the meal, changing the infusion site, making a more substantial insulin correction, getting on my exercise rower for 15 minutes, or some combination of these and more.
I’m not sure of the correct terminology, but I think of the DP as part of a circadian rhythm and FOTF as related to when I actually get out of bed. If you get up at the same time every day you can’t untangle them.
I often get up earlier or later than normal. The purely circadian portion (DP) is well controlled by changing basal insulin levels (elevated from 3am to 10am) on my t:slim pump, the actual getting up (FOTF) is not. Which tells me I should work harder to get up at the same time every day.
My experience, so it’s my DP/FOTF, demonstrates that AAPS does not handle my personal experience amazingly well. Nevertheless I regard it as adequate, “Could do better.” I frequently have peaks in the morning. If I’m being “proactive” (the in phrase in management when I was in my 30’s) I just bolus 2IU and let AAPS deal with the result; AAPS handles the apparently OTT bolus and nothing much changes.
Ok, I’m dissing AAPS; the reality is that I have a spike but so what? AAPS fixes it eventually. Many non-Ds have spikes, why should I expect to be better? So I just ignore it and that works most of the time.
I have exactly the same experience except that I don’t detect a circadian part these days (I’m not sure I ever did); I use AAPS and it can handle the elevated, or the lowered, BG with no problem so long as it happens slow. I use a fixed basal but that’s pretty much a fallback with AAPS; if everything goes curfluey and my 'phone (therefore AAPS) or my CGM dies overnight I’m remarkably stable with that basal. AAPS corrects for my evening excesses.
For me FOTF isn’t getting up; that doesn’t cause the spike. It’s ingesting. Pretty much anything (though I haven’t tried the obvious scientific experiment of drinking a glass of water and seeing if that gives me a spike, tomorrow, as the say in Mexico.)
What we need here is one of those Artificial Idiot things, which just looks at what happens and deduces the patterns. There must be some answer to this but we really don’t have to understand it; just fix it!
This would answer my concern if I ever must spend time in a hospital under the care of doctors, nurses, and dietitians. An automated electronic pancreas that needed an idiot to monitor my glucose metabolism would work well. I could instruct hospital caregivers to just leave well enough alone – the artificial idiot is in charge!
Feet on the floor syndrome causes a rise in BG that begins as you get out of bed. Different from dawn phenomena which is when BG rise starts a few hours before waking. Both are probably the result of fight or flight syndrome with cortisol and other hormonal releases causing the liver to release glucose.
It’s more complex than that, but that’s the basis.
There’s also the rise which I and at least one other recent commenter sees where our BG spikes in the morning the first time we eat or drink anything other than water. That pretty much has to be release of glucose from the liver but in this case it’s triggered by any morning consumption.
I think I’ve most commonly seen FOTF used to describe a drop in BG on getting up. In some ways they are all the same because they correspond to BG changes which cannot be explained by ingested food. So that’s either a change in the level of glucagon released by the alpha cells or it’s a change in response to a fixed level of glucagon in the liver. In the first case the most extreme effects might be expected in fully developed T1s where there is no beta cell insulin production to moderate the alpha cells.
I became keenly aware that my blood glucose levels rise very shortly after getting up when I got the G6 C and began taking Synthroid. The thyroid med needs to be taken fasting and continue to fast for at least 30 minutes.
My BG would rise in the 5 minutes or so after rising and before taking the thyroid medication. It would continue to rise unless I did a correction bolus.
A pump that is using a fixed algorithm like the t:slim CIQ won’t compensate adequately for DP/FOTF, but those using a dynamic, “learning” design might do better.
On previous pumps, I had DP and I programmed in a basal rise starting at 3AM to account for the rise. After I retired and didn’t have to go to work/ commute every day, my DP went away. For me, I decided that DP was all stress-related. For nearly 15 years, I never needed any morning bolus bumps to counter DP/FOTF. It just wasn’t there. Just over a year ago, I started having FOTF, but it’s very hit or miss. It’s not unusual to wake in the 93-110 range, and by the time I’m fully awake and getting dressed, I’ll be in the 130-150 range.
I changed by correction factor, my I:C ratio and it’s helped some, but some days my BG is off for the hills. I also use Sleep Mode 24/7.
That is what I do with Control IQ. I essentially double my basil a half hour before I get up. If I sleep late, Control IQ makes the necessary adjustments.
I’ve been using the twist pretty well for six months. We’re very few low blood sugars. Lately I’ve been getting low blood sugar at three in the morning or five in the morning so no matter what I eat or don’t eat. last I had with my Endo. He adjusted my Carb ratio down so I’m thinking of putting it back to 10 because low blood sugars they’re happening when there’s no indicator like at 10 o’clock at night. You have any opinion.
