For those who don’t know: pre-soaking is the practice of inserting a new CGM sensor way ahead of time before switching over your transmitter at the end of a session. This is supposed to ameliorate the instability a lot of us see during the first hours of a new sensor, sometimes taking as much as 24 hrs to settle down and start giving accurate readings. There seems to be a lot of YDMV in terms of how long people need to do it to see a good effect, but do you need a really long time, like 24 hours, or will a couple of hours do it—some say 8 is plenty, maybe less? Worth determining because it has a bearing on how inconvenient the whole business is.
In that light I’ve been carrying on a kind of informal experiment over my last several sensor changes (I’m using a Dexcom G6) to see if I can figure out what my sweet spot is. Here’s what I’ve seen over my last four, including the one I started today:
- Sensor 1: pre-soaked 6 hours. Result: flakiness settled down within ~8 hrs.
- Sensor 2: pre-soaked 8 hours. Result: flakiness settled down within ~8 hrs.
- Sensor 3: sanity check. Is presoak doing anything for me? Didn’t presoak at all. Result: flakiness for 24 hours.
- Sensor 4: pre-soaked 12 hours. Result: came out of warm-up 2 hours ago and hasn’t been erratic at all. I’ve done 3 finger sticks and it’s been within 8 points the whole time. More important, I’m not seeing those sudden zig-zag ups and downs that are the hallmark of the phenomenon and tell you you can’t really rely on what your numbers are yet.
Two hours is probably too soon to be absolutely sure, and I’ve just bolused and am about to eat lunch, so we’ll see how it goes. But so far it’s looking like a 12hr pre-soak is my sweet spot. What’s yours?