If you have the Minimed RTS then your pump will remind you to calibrate every 12 hours. If you dont calibrate, it will shut down, unfortunately. The reason this was put in was because the FDA is not an organization that you can just dump a CGM that replaces BGs and expect approval. You need baby steps in approval to get to the final goal of a complete replacement of an existing technology. So, Minimed introduced this whole calibration thing to appease that.
It is completely necessary to enter a value into calibration, but it doesnt have to be the one from your meter (sneaky huh?). If you hit that stride where your sensor will match your meter BGs, try and calibrate from the sensor reading rather than the meter. Your sensor will take the last 4 calibrations and factor them into transforming your “isig” into an actual BG, so when you add a calibration - it will calculate a new formula. Technically your CGM should match your BG to about 10 pts. Remember, it is reading interstital fluid and not the parts of your blood so it may be a little different.
Your best bet if you have WACKY readings from the CGM is to call Minimed’s 24 hour help line (if you have the RTS). They will take you through step by step in how to make sure your sensor is calibrated correctly. Truly a great service that has helped me numerous times.