CGM Sensor Interference and Noise

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.