This forum is new for me, so this may have been discussed and I haven’t been able to find it. If so… sorry! and please point me to the right place. I also apologize for the length of this post…
I graduated from my old Minimed/Medtronic pump (the last of about five) to a new Tandem t:slim (and who came up with that name?! plus a Dexcom G6 in January/February. Since I’m on Medicare, they couldn’t ship me one of the new pumps with Control-IQ technology, just Basal-IQ. I thought I’d have to wait until Control-IQ was approved by Medicare before I could get it. But apparently not! I just finished the training videos for Control-IQ, and have gotten the link to download the software. Don’t tell the feds…
But I have a couple issues I’d like clarified. First: users and professionals have been telling me that the true value of the Dexcom CGM is to let me be aware of trends and patterns, not to provide precise numbers that match your blood glucose (I’m sure you’re all aware that CGMs don’t measure BG, right? And sometimes the two don’t agree well with one another.). But… both Basal-IQ, and even more so Control-IQ, DO use the CGM data as if it was accurate BG data. There are several numerical parameters in Control-IQ that control its behavior (when your glucose is due to go over 160 within the next 30 minutes, for example, the pump starts ramping up your basal rate). So it’s interpreting the Dexcom values as BG values to do its control thing.
When the Dexcom values are close to true BG values, no problem. I’ve had that be true for several of the sensors I’ve used since January. But not always! Today, for instance, my new sensor started out with values 30-40 below the true BG values. At one point, it shut off insulin delivery altogether because it thought I was at 105 and going down, whereas my glucose meter told me I was at 165 (and it turned out I was NOT going down! So the Basal-IQ was misbehaving.
I know I can correct such differences by doing a calibration, which I did today. But: I’m given to understand that one should avoid calibrating if possible, and that once you start calibrating a sensor you can count on having to keep doing it for the rest of that sensor session; and I have a tiny bit of experience that supports that. Sometimes it seems I can just wait through the first day and the sensor “fixes” itself, and runs close to BG from then on. But that would mean my pump doesn’t work properly during that first day of the sensor session, and that would mess up Control-IQ even worse. And maybe give me false alarms all day.
Any advice? And if any of this is inappropriate for some reason, let me know that, too.
I will say I love the t:slim, for several reasons. I’ll put up with having to do the frequent calibration route if I have to, but that was one reason I rejected the Minimed 670 route (only one of many reasons, though . I think I’ll be installing the Control-IQ technology in my pump in about four days, as most users seem to like it and its features look very nice. But I can hang with Basal-IQ if I find that seems a better choice.
Just FYI: I was diagnosed with T1 back in 1960, so I’ve had some experience with various types of therapy. Dealing with T1 may be a bit of a hassle now, but I’ll tell you it’s WAY better than it was back when I had to boil my glass syringes!