Moving on from Loop to the Tslim

So, after more than 5 years on DIY systems, and around 3 Looping, we are moving on to our first commercial system for automatically dosing insulin – the Tslim with Control IQ.

We started Samson on a DIY system when he was just 2 years old and still in diapers; Mitch had to build it with an old Raspberry Pi and it took weeks of late-night coding sessions to set up. That first mii computer literally caught fire, and we moved onto more and more sophisticated hardware and interfaces. The most recent build of Loop took maybe an hour, so it has come a long way. We feel so incredibly grateful for the DIY community, and for all the years of great control it provided.

But the last year of Looping has been rough.

Ultimately, it came down to the Omnipod cannulas. We had to migrate from changing sites every 3 days to doing so at least every 2 days, if not sooner. We would have tons of unexplained highs with ketones which never occurred with the steel cannulas we used before. And the site changes were extremely painful. Pretty much every time we change out the Omnipod, there is dried blood on the cannula.

And as our son has gotten older he has become more mobile. Not having to remember to bring around his phone and OrangeLink became a bigger and bigger issue. The Tslim will work even if we can’t see his numbers, meaning we don’t have to nag him to go get his phone or OrangeLink every time he leaves a room. Also, I don’t have to do things like update the firmware on a mini-computer if it’ dropping signal all the time. And I’m hopeful we won’t have to fiddle with his settings all the time, like we do with Loop.

I have no idea if ultimately we are making the right decision, and I’m a little nervous that if the Tslim doesn’t work out, we won’t have other options – maybe we’ll have trouble going back to the Eros pods needed for Looping, for instance. But I’m ready to rely on a system that is a little more off-the-shelf, and requires less babysitting from either me or our kid.

Anyways, I’ll try to document how things go. I suspect the control will be a little less good than Loop on a good day. But if we have fewer bad days, with failing sites, it will be better in the long run.


If you aren’t after a perfect A1c, I think you will enjoy the automated nature of the Tandem/G6 solution. My son has recently been in the low 6’s with almost no effort on his part. That has been a god send as he is off at college and isn’t wasting any brain cells on diabetes.


We were typically in the 6.0 range and had been for about 2 or 3 years, but the past three or four A1Cs have crept up to about 6.2 to 6.4, in large part because if you spend every three days at HIGH for a few hours till sites are changed out, it’s hard to stay in the low 6s.

I would like to get him back down to where he was before. His A1C is almost always lower than his eAG predicts, so I think this should be very doable.


You will most likely want to run in Sleep Mode 24/7. This seems to work the best for most of us using the Control-IQ on the t:slim pump.
Also, what insulin are you using. Fiasp works great, but can have issues with the cartridge setup that the t:slim uses.
Lots of stuff to read here about the Control-IQ and how to tweak it for best results.
I have contemplated going DIY loop many times. But I like the simplicity of Tandem/Dexcom. No failing links, extra equipment, etc.

It isn’t perfect, and isn’t for everyone, but I think most people are seeing good/really good results from it, with minimal issues.


Depends on how often he goes high, since no bolus would be given, and increased basal may take awhile. But if he is able to do manual bolus for high bg, it would work.

You can try both ways to see what works best.


Definitely try both ways.
I think for those that are more insulin sensitive rather than resistant, either method may work fine.
I personally dislike how long it takes for the system to react to something that is going higher than I want. By the time it reacts, for me, I will definitely go pretty high before it does anything really.
The Sleep mode may not bolus (it’s only a 60% bolus anyways,) but it starts to react much sooner. And that makes the bigger difference for me.


We tried this when we did the trial and it did not work out great for us. I think it only works if your basal rates are fairly high relative to your ISF. For us, we might need to give 2 units correction, but Samson’s basal rate maxes out at 1 unit per hour. So there’s no way fix things as fast with basals. WE got lots of yo-yoing in sleep mode all the time.

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Yes, I have a higher basal rate. But not really that much higher than needed.
I run a much more aggressive carb ratio and correct ratio.
These allow for a much larger range for the pump to work within.

I am somewhat insulin resistant, so I have to use larger amounts of insulin to do the job. And I often eat some REALLY carb heavy meals.
Even with those two setbacks, I can get pretty good control. I maintain my A1cs in the 5’s this way.
I do have to use a faster insulin though. I use Lyumjev or Fiasp. Both work almost the same for me. I don’t even change my profiles when switching insulins.

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Very sorry that the DIY loop hasn’t worked out for you all but I’ll be watching for your future updates on the Control-IQ system! We all have to find what works best for us so I know everyone here supports your decision!

Keep use posted!


we shall see; I don’t think it’s the DIY that didn’t work, and more the Omnipod sites seemed to not agree with him.

Though we are now dealing with hours at HIGH with the new Tandem pump so I am wondering if it might actually be an insulin absorption issue. Our endo switched us to Fiasp around 6 or 7 months ago – the site issues we’d had with Omnipod were the reason, but I wonder if the Fiasp is also adding to the problem.


Tia, I’ve mentioned here before, but I also tried out Fiasp using OmniPod and Loop. It initially worked about the same as Humalog, but for some reason, it eventually stopped working for me. My insulin sensitivity became much reduced and I was also constantly fighting highs. When I switched back to Humalog, my insulin sensitivity returned back to what is normal for me. Maybe you can try Humalog or Novolog and see if either helps.


Novolog has always been what we’ve used and it’s never let us down, thankfully.


Yes, I think it’s either the Fiasp breaking down after 3 days, or I’ve read on some forums that the Tslim doesn’t work when there’s less than 10 units of Fiasp in the cartridge somehow? Which is going to be rough for us as the Tslim needs a minimum of 120 units to fill up, so we may be wasting a ton each time.

In any case I’m going to check in with our endocrinologist because these highs are miserable and horrible for Samson. And they undercut the days and days where he stays under 140 almost all day.


I will also say once I decided to religiously change out his Omnipod no matter what at 2 days OR at the first sign of a high – be it 7, 17 or 48 hours after insertion – his numbers with Fiasp were phenomenal – hours in the 80-110 range and only brief blips above 160 or so, even with huge meals.


But the problem is that Samson absolutely hated the site changes, so having to change every 2 days was pretty agonizing for him.


As were mine. I’ve been doing this for nearly 60 years and FiASP was easily the fastest uptake insulin I’ve ever used, by a country mile. Until it wasn’t :woozy_face:

It simply stopped working for me (and while I had it in my pump, my mealtime boluses were all done via injection). I tried new vials and still it was like injecting water.

While I still have a vial of FiASP in the fridge, I currently use NovoRapid (what Novolog is called in Canada) in my pump as it performs more consistently than Humalog for me.


3 posts were split to a new topic: Fiasp, Lyumajev, and other Fast Insulins