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February 2024
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It’s been an interesting week

I’ve had a Tandem T-slim pump since January and not had a great deal of success running the “closed loop” (there are so many wrong things about that statement, that yes, I have put it in quotes, more about that later).

Coming up to my 45th diaversary, I am kinda familiar with what I need to do to ensure that part of my endocrine is doing what’s needed to keep me alive today and in the future without too much bother.

Anyway, my son believes this is “my worst pump ever” and being 22, he is quite aware of this. I got my first pump just before he was 1.

Back to the reason for this post…

There is a reason?

Yes! I have tried with letting the pump make adjustments but it’s not been very successful. I have key parts of my day (the daily commute for instance) where my blood glucose goal is a little higher than normal – 5.5 compared to 4.7mmol/l. I am sure there are some type 1 diabetics out there going “that’s low” but actually, it gives me a little wiggle room, a chance to play with a short term temporary basal rate or just have a cup of coffee to raise my levels a little if I need to. The beauty of a pump is it should allow that and, to be honest with you, that’s what I was hoping for from the Tandem Control-IQ software.

Unlike some systems, it is a self-contained unit and has some “learning capability” so it should learn what works. Unfortunately, when it came, my carefully set parameters were ignored when it was running the show – it wanted me at 6.5mmol/l. Which means I cannot sleep very easily because that is not where I feel safe. (Again, there may be type 1 diabetics out there gasping in shock, but after 21 years on the pump, I feel really quite high (hyperglycemic not, you know, tripping) if I run a that level.

Plus, it isn’t what non-diabetics do. They run much, much lower, which again was a shock when I bought a sensor for my husband to wear for 14 days.

Anyway, back to the piece. Running at 6.5mmol/l does have it’s advantages at times – the daily commute, running about at work, etc. Only to achieve that, the Tandem is very keen to stop my basal rate completely… Making me high and swinging much more than I had with my old pump: “worst pump ever” isn’t a terribly inappropriate way of looking at it.

Then there was the learning – out of the blue, it gave me 6 units of insulin as a “correction dose” which would have been a good move the day before but as my period had just started, caused an unexpected and fast on-coming hypo (glycemia). That wasn’t a fun day at all.

So, I turned off the loop for the majority of the time but especially during the night. I was tired (literally) of waking up with a blood sugar of 9mmol/l at 2am because the pump had turned off my insulin just when I needed it.

Six weeks ago, an update for the pump’s software came along and I have been re-experimenting (well, what would you call it?) with the pump.

And it seems to be working. This is the 5 day I’ve been running the loop (over night as well) and it seems to be doing a much better job. Over course, one thing I did make an effort on was getting my basals perfect, but it seems to be doing reasonable things much more consistently. It’s not perfect: there are odd occassions where I’m still calling it “Stoopid” but these are much rarer.

It actually feels like it’s workable. Of course, it cannot tell when to change my basal rates, but if the basals are good, it seems less keen on shutting down my insulin indefinitely.

What is it “closed loop”?

Pancreatic transplants are very tricky to get to last more than 5 years, so one of the ways being investigated for long term treatment is hybrid loop insulin pumps – the Tandem T-Slim is one such offering.

One of my big complaints about these and the way they are used, is they want users to ditch their hard won basals and start from scratch. As a type 1 diabetic, I think that’s naive and missing the point – I know far more about what’s going on that something looking at just my basal rate, last active boluses, and my blood glucose reading which is how all these pumps work.

I know, for example, that on a Sunday I don’t bother bolusing for breakfast if it’s my turn to cook Sunday lunch – I am running around the kitchen so much that doing my normal bolus will make me hypo about 45 minutes after I take the extra insulin to cover my yoghurt. I know if the temperature is 16° instead of 20° I am likely to need less insulin. I do this by switching basal rates not putting in temporary basal after temporary basal.

Until these pumps take our knowledge and needs into consideration, they are unlikely to be as good as their users for anything but shutting off much needed insulin. Maybe the new software for the T-Slim has finally figured that out.

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