CGM Sensor Interference and Noise
CGM accuracy is challenged by three primary noise sources: electrochemical interference, mechanical artifacts, and biological noise from the body's immune response.
Reviewed by CGM AFIA Editorial Team. Last reviewed: 2026-01-24.
Author: CGM AFIA Editorial Team
Part of: Accuracy and Interstitial Lag Time
Overview
CGM accuracy is challenged by three primary noise sources.
1. Electrochemical Interference
Substances like Acetaminophen and Vitamin C are electroactive and can oxidize at the sensor electrode. This creates extra current that the algorithm misinterprets as glucose (false highs).
Modern Solutions
- Permselective membranes block most interfering chemicals
- Hydroxyurea remains a critical contraindication
2. Mechanical Artifacts (PISA)
Physical pressure on the sensor restricts local blood flow and oxygen supply. Since Glucose Oxidase sensors are oxygen-dependent, this depletion causes a signal drop.
Compression Lows
- Cause false hypoglycemia readings
- Particularly common during sleep
- Often called "Pressure-Induced Sensor Attenuation" (PISA)
3. Biological Noise
The body's Foreign Body Response (FBR) leads to:
- Protein adsorption (biofouling)
- Fibrous encapsulation
This creates a diffusion barrier that alters sensor sensitivity over time, necessitating complex algorithmic smoothing and calibration to prevent signal drift.