Could a closed-loop system deal with my use case?

I want a closed-loop system very, very badly. However, I think I’d use it more on a part-time basis. I’d continue to test and manage my own blood sugar at times, but use the loop system at other times (especially overnight).

I also think it depends greatly on your level of control… I can understand why folks with an A1c of 5.2% and 95% time in range wouldn’t want to give that up. I’m dealing more with an A1c of 6.8% and 70% time in (a wider) range (than someone with an A1c of 5.2% is probably using). So, for me, I definitely think a closed-loop system could improve on that control.


But there’s nothing wrong with a 6.8. That’s a great A1C. Going lower is great, but I haven’t read any studies (maybe they do exist) that quantify the level of “extra life” you get from lowering it to 5% A1C. Long-term complications don’t exist with a 6.8 to a large extent and we’re personally happy with the 6.8 we have for Liam. The issue with any loop system is that, from what I’ve read and researched, there are a lot more frequent severe lows with the system…and we just don’t need, or want, to trade a better A1C for more severe lows. If the system is going to give insulin based on a reading from interstitial fluid glucose, then he’ll be severely low (dangerously low) quite often, since our CGM is frequently 50 off…more in rapid movements.

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Which group are you in? You’re technically already using a semi-closed-loop system with the t:slim Basal-IQ… :slight_smile:


I don’t think there is an A1c cut-off at which complications don’t exist. Everyone with diabetes is at a risk for developing complications. All you can do is lower your risk, and as far as I’m aware, studies have shown that, hypoglycaemia aside, the closer you can get to a “normal” A1c, the lower your risk. They have not really done studies at A1c levels below 7% since the majority of people are not able to hit that target, so it’s simply unknown whether reducing the A1c further may help or not. My guess is that it does help but at a certain point the effort needed (for many people) to maintain such tight control and the risk of hypoglycaemia outweighs any benefits to a lower A1c.

But if you can get closer to normal with no greater effort and reduced risk of lows, I’d definitely take that. I have not seen anyone mention more severe lows with the closed-loop systems. I have read about people loving Loop and loving Basal-IQ and how they are able to maintain more time in range using those systems. I have heard of people hating hte 670G because of highs since it is not aggressive enough. I really have not heard any complaints about lows, but I’d be interested in where this information has been posted.

Plus, for me it’s partly a quality of life issue. At an A1c of 6.0% I actually had fewer lows and diabetes was just far less of an issue than it is with a higher A1c and more variability and out-of-range results. Of course the trade-off, which I’m not willing to make at this time, was eating a low-carb diet. But if I could achieve those same quality-of-life benefits—sleeping through the night most nights, not having my CGM alarming constantly during the day, not having prolonged highs that wipe out my productivity for an afternoon, not having to watch the CGM constantly, having less issues with insulin sensitivity changes related to hormones or exercise or illness—I’d take them ina heartbeat. So if a closed-loop system can provide that, or even a step in that direction, even just part of the time, I’d take it.

One of the hardest things I find about diabetes is its constancy. It’s always there, day and night, day in and day out. I can never, ever, ever, ever take a break from it. And usually I don’t mind, I’ve been doing it for over 27 years and so in many ways it’s just built into everyday life. But there are times, especially when I’m overwhelmed with non-diabetes things and diabetes decides to go on a rollercoaster on top of everything else, that I feel like even just one day of not having to worry or watch or make constant decisions would be a huge help. Diabetes is always 100% me, there is no one else I can rely on or turn to for help with management. So even if a closed-loop system is something I’d only turn on during those times, even that would be helpful.


Well we are closed loopers, so obviously we’ve chosen the dark side :slight_smile:
All joking aside, I get that some people have discrepancies with their CGM/BGM numbers and so don’t find those numbers actionable. I would argue (and probably someone with more time on their hands and more fondness for statistics could actually prove) that closed looping with CGMs we have now, with existing accuracy, will yield better results Y percent of the time than either a) finger stick and CGM with pens or b) CGM with confirmatory finger sticks and manual mode pumping. Of course it also depends on what you consider good control. I’m guessing someone who has a really tight range, like 80 to 120, and considers the difference between a 120 and 140 to be catastrophic, would not do well with a closed-loop system. But for us, we usually have a lot more leeway in our ranges. And so do 99% of type 1s.

Personally, I’ve almost never had a situation where the cgm said “high” and Samson was low, for instance – which is the most dangerous. Usually it’s that he’s a little higher than the CGM suggests, or that it way overestimates the depth of a low and has a lag time, but we find it’s almost always within 10 percent, which is good enough for us.

I’d also say we are achieving a pretty low A1C with some pretty approximate bolusing, no dietary restrictions and some pretty sub-par caregivers at school. So to me the tradeoffs are pretty apparent. I can’t imagine that in 10 years anyone will legitimately consider manual mode pumping to be better than closed looping.


Make no mistake about which side is which. I am the one on the Dark Side. image



And I was on the 670G for over a year. It was all I needed to see to never trust any kind of automatic anything ever again in my life. If someone said I had one way to get across country, and it happened to be in a self-driving car that I could keep at the end of the trip, I’d start walking.

There is a glimmer of light in the t:slim. There really is. The poor thing is coming up in my 670G’s shadow, so it really has an unfair starting point. I’d be thrilled if it turns out to better… and in complete and utter disbelief if it turned out to be worse. :scream: And considering drafting a blanket apology to Medtronic for the few things I said over the last year…

I guess I just feel like with where technology is, it’s not necessarily any less work to get good results. I know we’ve all got different needs, different standards, different strengths and weaknesses, and so we won’t all agree, but there was something just right about MDI and finger sticks. Until I can actually trust any of these devices, I’m kind of just swapping out one burden and inconvenience for another.

I’m pulling for the t:slim. I really am, but I’ve got my bag packed and ready for MDI in case it doesn’t pan out.


It all starts with the cgm sensor.

It takes far more than that for actual success but if you don’t have a good accurate sensor then may as well give up and don’t even bother going further.

A good accurate reliable consistent cgm sensor is a basic requirement for any sort of automation.


Kind of along the lines here: I had a 1st happen to me today! Double unicorn. BG was 54, dexcom (day 13) was 54, and guardian (day 6) was 54! woah :exploding_head:

It’s not always copacetic, but I am hopeful for the next 10 years with CGMs and closed loop systems


I, on the other hand, cannot wait until blind people are able to drive those self-driving cars. I’m not sure I’ll be first in line, but I’ll have no hesitation once it passes all the tests and the early adopters test it out. Hopefully it’ll happen in my lifetime.

Having a car is such a luxury. It’s like having a small, detachable piece of your living room. You get to set the style, the temperature, the music, have a personal coffee holder, personal power outlets for all your devices, personal storage space, and can set your own schedule.


And I can understand that completely. That was why I said we won’t all agree. It’s true for diabetes technology as well. I have terrible lows, but they are not out of my control. When I hear someone who has had repeated episodes of hypoglycemia so profound they’ve been carted off to the hospital in the middle of the night, I completely respect their perspective on the importance of their CGM. I would never argue with them over the lag or the cost or anything. In my case, I’m lucky in that I’ve got some wiggle room. Things change, and I easily could find myself, with just the slightest shift in priorities, longing for the self-driving car, too. Just so happens I’m really enjoying traveling by foot at the moment, so that could also be tainting my view. :grin:

I’m not that interested in a closed loop system, but the pump is more of a deterrent for me than the cgm (dexcom).

In order for me to be willing to use a closed loop system, the system would need to use much faster insulin and include glucagon somehow. I might consider a system with fiasp and glucagon.

Even then, I had lots of scarring and consistency issues on a pump, and I hated having it attached to me.

The Dexcom is pretty accurate for me. If the pump wasn’t an issue for me, I’d probably be using a closed loop system now.


No, @ClaudnDaye, this is not true. The opposite is true: with a closed-loop there are in general fewer lows.

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In kids this is not the case. Due to their insulin sensitivity and requiring so little insulin to take major nose dives. That is probably very true in adults where .05 or .10 isn’t that big of a deal but someone Liam’s size it matters a lot.

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But Samson is looping too, and doing fairly well, though.

She’s expressed quite a few issues she’s had with the system also. From incorrect DIA’s causing crashes to constantly have to manually manipulate the system. I think she’s expressed (although I can’t find the posts now) quite a few issues with lows using the system.

For me, it’s very simple.

Does the closed-loop system treat based on the CGM reading from interstitial fluid glucose? Yes.
Do I want any treatments based on any reading from interstitial fluid glucose?
Therefore, I would never go closed-loop until some other means of BG (blood) was come up with and treatments were made based on those readings. For us, the CGM just isn’t accurate enough to do any treatments with right now.

The CGM is late, and typically incorrect for Liam…I don’t want any system to give him insulin thinking his BG is 130 when it’s actually 80.

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Except when treating lows more than once, we treat based on CGM numbers, and we are pleased with the results. So, in our case, I don’t see a problem with today’s sensors in a closed loop system.

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This is very much a YDMV. Each person seems to have a different experience with the CGM’s accuracy. For us the value in the CGM is definitely in the trending.


I know everything is much more difficult with little kids, which is why I am so impressed by how phenomenally well Liam and you are doing. I also understand you have good personal reasons to be skeptical and that’s perfectly fine - of course people should do however they feel works best for them. It’s just that as far as I know there is absolutely no evidence for the statement that there are a “lot more frequent severe lows” with any loop system. That’s just not the case, for kids or adults.

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so, we do have lows and occasionally they are potentially related to the closed-loop algorithm. But most of the time they are made much less severe because of it.

We have fewer crashing lows now than we did when Samson was not closed looping. And the vast majority of steep lows occur when I bolus manually, rather than letting the closed loop algorithm do its thing.

that said, there are certainly more “knobs” to fiddle with and there are times when we may have lows because Samson has changed and his settings should too, but we just haven’t had the time to modify them. I suspect we’d be changing the settings more aggressively if he was not in a closed loop because the problems would be much more apparent earlier – he’d be running much higher or much lower and so we’d fee like we have to change something ASAP, rather than letting some wrong settings linger for a week or two because the effects aren’t so horrible. We never carb-count super precisely, and i suspect that’s in part because we started out our journey closed looping, and so we can get decent results without doing that – and because trying to figure out if a carb ratio is right or wrong when looping is much harder than in manual mode. I think looping allows people to either a) get really, really tight control or b) get decent control while being a little sloppier or less vigilant. We are closer to option b). So there are all sorts of subtle ways that looping could be leading to less optimal blood sugar management.

But as far as lows due to closed-looping amplifying inaccuracies in the CGM reading? We have almost never encountered that.

So I would categorically disagree with the statement that closed looping causes more lows in kids.

That said, it certainly takes a lot of work and I don’t think it’s the right choice for everyone. And when Samson was off openAPS for a while it was fine and his BG management was almost the same during the day. But at night? It was a nightmare. So much more running high, much more running low, low low at night. There’s a reason we went back to Looping despite how much of a PITA it is to fiddle with the hardware, the connection issues, and the settings.