As a sensor ages, its accuracy diminishes, and its correlation with interstitial fluid glucose deteriorates. Noise refers to the rapid, oscillatory fluctuations in readings caused by sensor malfunction, rather than true variations in your blood glucose levels.
Consider the readings in the following image:
The glucose level increases from reading A to reading B, then decreases from reading B to reading C. However, the time interval between these readings is only 5 minutes, which is too short for such rapid fluctuations in blood glucose. This discrepancy indicates sensor malfunction (noise). In this case, you can either switch to a new sensor or tolerate the erratic readings until you do.
