I started a new Dexcom G6 sensor using my Tandem pump and the code. About 10-20 minutes into the warm-up I got a LOW alert and it has been reading LOW ever since. I called Dexcom and they’re sending a replacement.
I’m now wondering whether I should leave the sensor in and see if it starts giving accurate readings in an hour or so (it’s now been 40 minutes since insertion) or if I should pull it and start over. I guess I’m leaning toward pulling it because I don’t want to go through a second two-hour warm up period if this doesn’t work, but I’m also kind of intrigued.
Has anyone else had an inexplicable no-warmup Dexcom session? I’ve used a lot of sensors and this has never happened to me before.
That is bizarre; I’ve never had that happen. I would have taken it out, contacted Tandem, and put in a new one.
Nope, I have never seen that. That’s an odd failure.
Tnyc, if you do decide to leave it in, you need to turn off Control-IQ. If your pump thinks you are really LOW, it will turn off your basal insulin, which you don’t want if you BG is normal.
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I left it in (with Control-IQ off) and it quite suddenly stopped reading low and started giving fairly accurate readings about 1 hour and 20 minutes into the warm-up period. (Interestingly, there wasn’t really a transition period – it went from low to somewhat accurate without any in-between readings.)
I believe xDrip users can see data before the two-hour warmup period is over and I’m curious if they have the same experience. I.e. that it doesn’t really take a full two hours for a sensor to start giving useful data and that sensors read low when they are warming up and then abruptly start giving accurate data.
I’d actually like to recreate this experience with my next sensor in order to shave 30-40 minutes off the warmup period but I have no idea what caused it.
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Maybe it’s a new “feature”? The G7 supposedly has a much quicker warm up period . . 
Not anymore. Dexcom changed the software and it doesn’t share that raw data anymore. I wish it did!
I’m a little addicted to the data and go through withdrawal symptoms during that 2-hour warm-up without it. I’d rather sketchy data than none!
I did have a sensor do what you described once, sorta. It was giving random data dots and mostly “- - -” instead of the warmup countdown, but it failed before the 2-hours passed and I had to change it.
This makes no sense to me. Your dexcom should not be giving any data at all during warm up. It should show blank. The reason for this is, the first 2 hours are unreliable. If you are getting data during warmup, it’s not the sensor. There is something wrong with whatever you are using to receive the data
I agree that it’s not the sensor. It must be a software anomaly. I use a Tandem pump and the Dexcom app on my phone. I’ve started many many sensors before using this software and this is the first time this has happened. Very odd.
I’ve had multiple occurrences of this, and I always have DexCom replace it. But in the meantime, I do a calibration, but following a special protocol:
- do a fingerstick.
- enter the value in the X2 pump as a calibration.
- immediately do another calibration using the same reading.
The first calibration causes the Dexcom to split the difference between what it thinks and the entered value. The second one forces it to be your meter reading.
Sometimes I’ve had to repeat the above about an hour or two later. But after either one or two such calibrations, the sensor gets its head on straight and works right for the rest of the ten days. I do check it if things don’t look right, and a repeat of the LOW alert (when not warranted) would cause me to replace it.
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I think you’re misreading what happened. I’m not saying I got a false low after the warmup period (that happens), I’m saying I got a reading 15 or 20 minutes after insertion. I wouldn’t expect any readings then and I definitely wouldn’t expect accurate readings. Way too soon to think about calibrating.
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This has happened to me twice. Both times the sensor settled in and I ended up wearing it for the full 10 days. I never looked into why it happened.
It’s calibrating itself during this warmup period. That “calibration” period is where it tries to figure out how to provide accurate data.
An update: the sensor worked well for the full 10 days.
The mystery of how to recreate that particular software hiccup which effectively shortened the warmup by about half an hour remains.