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May 2024
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A year and a bit in

On the 13th Jan 2021, I got my Tandem TSlim with Control-ID.

This is a hybrid closed loop continuous subcutaneous insulin infusion pump. Working with my Dexcom G6 (an update for the G7 is due at some point, as per but not yet), it can learn how to correct high and low blood sugar.

The promise is that the TSlim should do much of the heavy lifting in terms of my day to day control. This is a review of the past year.

Firstly, Tandem themselves admit that you need to exercise “responsible Use of Predictive Technologies”. These are early days of such technologies and they do have limitations. Getting Covid-19 in February 2021, I had to turn off the Control-IQ functions or I would have ended up in hospital with ketoacidosis – when type 1 diabetics don’t have enough insulin, our bodies burn up muscle and fat (yes, in that order) to provide energy to live which we then cannot use but creates acidic levels in our bodies which can cause immense damage to our kidneys.

On the day I got the Tandem, my HbA1c was 5.6% – a good result. Three months later it was 6.5% – not the direction I want to be going!

Most importantly, fighting infections mean generating a fever and that means dumping lots of glucose into our blood streams to “initiate a hypo” – the algorithm just wasn’t up to that task. I was, so I did the job. I was ill for three days and fought the infection well – a joint effort between me and the vaccines, I feel.

That doesn’t sound great!

I was a little disappointed. I also didn’t really appreciate how much the TSlim really needs to be on “solid ground” to work well. In my book, “How to thrive on insulin” I spend a great deal of time discussing the importance on basal rates and the TSlim is no different. If your basal is not perfect, the TSlim is not going to be able to make good decisions. As mine wasn’t quite there when I got the pump, it took a good while of basal tuning to get to the point where it wasn’t doing insane things.

For a woman, that’s a slightly different game we’re playing to the men. I have 5 basal rates I use during my menstrual cycle, one rate I use for only 3 days a month. Now, I have worked out that during those particular 3 days, I should not, under any circumstances turn or significantly reduce my insulin off for more than 15 minutes at a time – something I do do if my blood sugar is heading low and a small tweak will help. My basal during this time is significantly lower than any other time in my cycle as hypos (low blood sugar) are a little more likely – compounding that decision makes it very likely I will be hyper (high blood sugar).

The TSlim, after 13 months, has not come to the same conclusion. You can see Control-IQ doing exactly that, reduing my basal for more than 15 minutes and the resulting highs – gah! Again, not a time I can use the Control-IQ for significant amounts of time.

It also doesn’t seem to really appreciate food – my insulin takes 15 minutes to work, so if I have insulin when I eat, but the time I am digesting the food my insulin is there to make use of it. TSlim goes “you have too much insulin on board” and shuts off my basal – which can lead to very high blood sugar an hour after I eat. So I turn off the Control-IQ for meals.

Are you ever using this hybrid loop thingy?

The short answer is yes. Occassionally, when I do so, it does an OK job, if I keep half an eye on it. I am not running it 24/7 and not watching what it does – my HbA1c would be terrible if I did.

Exercising is one of the best examples of this – my recent skiing trip, it meant I just didn’t need to snack in the same way, switching on both the Control-IQ and the exercise activity. It’s not quick at reacting to the highs but it will do so.

I do not use the sleep activity – while Control-IQ will deliver a bolus to correct highs, the sleep activity will not do this! So, it can let you get in the high teens without effective treatment!

Now I’m properly over the Covid-19, I am looking forward to walking in the evening with my husband, which should not require me to do too much with my food and basal rates if I use the exercise activity with Control-IQ.

I don’t use the exercise activity with my long distance cycling as it will make terrible decisions in the first hour, dumping a load of insulin then shutting it off when I suddenly nose dive – no thanks.

I cannot get my early evening basal quite right, so I may play with the exercise activity to ensure I don’t need to take on extra CHO just to get home safe and sound.

Bearing in mind that I will have to turn it off the moment I walk through the door…

It’s not quite taking the load off my shoulders and it definitely is not a “cure equivalent” for me. It is getting to the point where it is not making insane decisions, which makes it a little bit more useful.

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