Not every sensor will need to be calibrated. Sometimes your CGM may be calibrated slightly higher or slightly lower than the true value. Both CGM devices and finger-prick devices are allowed by the FDA to have up to a 15% variation from what you would receive from a full lab draw at a physician's office.
The finger prick tests are like snapshots of your glucose. It only captures one moment. If you take a picture of someone jumping, you could catch them at the beginning of the jump, right when their feet leave the ground, or when they are at the apex of their jump. Each one of these pictures will tell us something different if we look at it alone. If we see the picture with the person's feet barely off the ground, we might not be able to tell how high they jumped or how long they were in the air.
The CGM is more like a video. Even though it only takes a reading every 15 minutes, we can get a good overview of the height and duration of the jump. We can view trends as opposed to focusing on one specific value. This way we can see that we jump higher after eating cookies compared to almonds.
The most important thing to consider is the overall trends rather than an exact number. For example, how much does your glucose increase after each meal, and then, how long does it take to return to your pre meal values?
To calibrate, we offer a manual calibration feature within the app. Check out this article on how to calibrate for more help with this!