Tandem T-Slim A Year On
I upgraded from my venerable Animas Vibe in Octover 2019 after having used it for about 10 years, to the Tandem T-Slim. I think the Tandem T-Slim is great and had been meaning to write up a few notes about it but hadn’t got round to it until now. This isn’t meant to be a comprehensive review, just some brief thoughts!
Charging
I charge it every day when I shower - this takes about 10 mins. It’s usually at about 90-95% charge beforehand and this takes it to 100%. So it drops 5-10% a day. You can’t use AA batteries - USB charging only. But if you have a power bank for charging your mobile you can use one of those to recharge your pump (eg if you are camping for a few days and without power).
The recommendation is that you do it this way (a little every day) rather than waiting until it drops low then charging it in one longer session.
Low glucose suspend
The low glucose suspend works pretty well if your glucose level is on a gentle-ish downward trend. If if is dropping rapidly (eg, you have a bit too much insulin in your system and you do exercise), then you definitely need to take some glucose on board. I haven’t had any problems with big rebounds.
At night I set the basal rate so I have a slight downward trend, and let the low glucose suspend kick in. This keeps me pretty much around 4.5mmol/l for most of the night. In the image above the red vertical bars are when the low-glucose suspend kicks in.
A couple of times I have woken up feeling pretty lousy, but when I checked my glucose level was between 4-4.5mmol/l all night. I did a manual test, and found it was mis-calibrated, and was actually 3mmol/l. So the T-Slim did a great job at keeping me in an extended hypo for 8 hours! Without the low glucose suspend this wouldn’t happen: you’d drop below 4mmol/l, the CGM would alarm, you’d have some sweets and be back up to 8mmol/l or so. So calibration before going to bed is important IMHO.
That said, my quality of sleep is much better now. Low glucose suspend during the night (when calibrated!) works really well.
FIasp
It didn’t seem to work very well with FIasp. I found that after 2-3 days, my glucose levels would sky-rocket and had to do a cartridge and set change to bring them down. This happened three times in a row. Two times were with a teflon cannula, but the last time was with a steel cannula. In all cases the cannula wasn’t kinked. I switched to Humalog and haven’t had the problem since. Chatting to some other T-Slim users on FaceBook, some people have been using FIasp without any problems, but one women had exactly the same problem as me.
Filling the cartridge
Filling the cartridge is a bit fiddly, but not too bad. You quickly get used to it.
Final thoughts
I think it’s a really great pump, and the low-glucose suspend works well. I had heard that the Control-IQ feature would be made available in the UK in 2020, which i’m really looking forward to.