Never Needs Calibration... Except When It Does

On March 5, I changed my G6 sensor as I normally do. No problem. The sensor inserted just fine, and the two-hour countdown started. At the end of the two hours, instead of the sensor just starting, I received a message across the receiver screen that said, “Calibration Alert!” Then it told me to take two blood glucose readings to calibrate my new sensor so that it would accurately reflect my blood glucose. I did as I was told, recalibrating both the Dexcom receiver and the Dexcom app on my iPhone.

All was fine until three hours later, when I received a message across both devices saying, “Calibration Alert!” with the same instructions to take two more blood tests to calibrate my sensor so that it would accurately reflect my blood glucose. Hah! So much for the G6’s “never needs calibrating” advertising ploy. Once again, I tested and recalibrated both the receiver and phone.

Today, at 12:02 a.m., I was awakened by a beep that told me “Calibration Alert” with the same spiel. OK. Now I was irritated. I hate to be woken from a sound sleep, so getting that failure in the middle of the night did not make me happy.

I called Dexcom this morning, and the Technician told me that the sensor was getting an interrupted signal. (No kidding.) He then said that I should remove the sensor and start a new one. He said that he would send me a replacement sensor, which I graciously accepted.

What did I learn? First, I should have called immediately when this happened right after the warm-up phase. I could have saved a few blood sticks by not having to recalibrate multiple times. Secondly, the old adage, "Never say ‘never’ " certainly applies to the G6’s “never needs calibration” claim. And finally, I am glad that I had extra sensors available so this did not become a hardship.

As a Medicare patient, I am out five blood sticks for the recalibration tests I had to take, but I know getting Dexcom to send me strips is not a fight I will win. Thus, I post this topic just to warn others that if you are on a G6 and get the Calibration Alert, perhaps recalibrate once. If it happens again, just call Dexcom and change the sensor. It will save you time, frustration, (perhaps sleep,) and a couple of blood sticks.


I’m just just curious and not presuming anything here, but could you have accidentally skipped entering the sensor code? I’ve never run a sensor without it, but my understanding is that this is typical behavior if you proceed without the code.

No. Since I have to enter the code both into the iPhone app and the Dexcom receiver, that is just part of the routine. The Technician did not seem to be surprised at all with the problem, so I think this is one of those “sometimes this happens” events. Dexcom was great about offering to send a replacement.

I had that thought too, but the double-calibration is only for the first one after warm up. This sensor was demanding double-calibration for the subsequent ones as well, which isn’t typical of the no-code session.

Thankfully, Dexcom was more than willing to send me a replacement. I changed out the sensor and have not had any problems with the new one. I guess in the orchard of life, sometimes we get a lemon.