Sometimes I get a "lost sensor" alarm when it doesn't seem to make sense, as you've described. My minimed nurse told me not to worry about replacing the thing in my stomach until a last resort.
Here are the steps I try anytime I get a lost sensor message.
- Move the pump closer to the general area of the sensor. Ex: front jeans pocket if the sensor is on my front. (Sometimes I forget and stick my pump in my back pocket! Oops!)
- Hit "Act", then choose "Sensor" > "Sensor Start" > "Find Lost Sensor".
- Wait a few minutes. See if that works.
If that doesn't find your sensor, then I do this:
- Unhook the white transmitter from the clear part that sticks in your stomach. (Ex: Pull off any tape you have covering the whole sensor/transmitter site. Squeeze the two sides of the clear thing, and gently slide the white transmitter away from the clear part that goes in your stomach.
- Wait 2 minutes.
- Hook the transmitter back up to the clear thing that goes into your stomach, just as if you had just put a new one in.
- Wait for the happy green light.
- Hit "Act", then choose "Sensor" > "Sensor Start" > "New Sensor".
- Pretend like you had just inserted a brand new sensor into your body (instead of just reusing what was already there). You will have to do the whole 2 hour wait, then 6 hour test thing, but it should work. And you haven't wasted a sensor!
My minimed nurse said there is no harm in using a sensor for a day longer or so, and the machine really can't tell whether the sensor is new or old - it just goes off of what you tell it.
Of course, do what your doctors/nurses/Mimimed reps have advised you. This is just what I was told to do - and it has worked so far. I have been using my Mimimed CGM for about 2 months now and have not wasted a single sensor yet.