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CGM INTERFERING SUBSTANCES & PROCEDURES 

See what medications, substances and procedures can affect continuous glucose monitoring accuracy.

 

 

Written by: ADCES staff and subject matter expert faculty

December 16, 2025

Interfering Substances That Impact CGM Accuracy

Health care providers play a crucial role in guiding patients with diabetes towards effective management of their condition. One of the most popular and valuable tools is the continuous glucose monitor (CGM), which provides real-time data on glucose levels. Before recommending a CGM to patients, it's essential for health care provider to have a thorough understanding of multiple factors, including possible interfering substances.

These substances, such as certain medications, vitamins or procedures, have the potential to affect CGM accuracy, leading to inaccurate readings and potentially compromising patient care. By recognizing and accounting for these interfering substances, health care providers can ensure more accurate and reliable CGM data, resulting in optimal diabetes management.

CGM Interfering Substances & Procedures

Guidance reflects current manufacturer labeling where available. If CGM values do not match symptoms, confirm with blood glucose monitoring (BGM).

CGMKey interferencesClinical actionProcedures
Dexcom G6
rtCGM Glucose oxidase 		Acetaminophen (high dose) Hydroxyurea
Details
  • Acetaminophen: at high doses may falsely elevate sensor glucose.
  • Hydroxyurea: can cause falsely elevated sensor glucose; risk of missed hypoglycemia.

Confirm with BGM when symptoms and sensor values do not align.

  • Confirm with BGM if readings do not match symptoms.
  • For hydroxyurea, do not rely on CGM alone.
MRI/CT/X-ray: remove Diathermy: avoid
Details
  • Remove sensor/transmitter before imaging per device guidance.
  • Do not use during diathermy therapy.
Dexcom G7
rtCGM Glucose oxidase 		Acetaminophen (high dose) Hydroxyurea
Details
  • Acetaminophen: at high doses may falsely elevate sensor glucose.
  • Hydroxyurea: can cause falsely elevated sensor glucose; risk of missed hypoglycemia.

Confirm with BGM when symptoms and sensor values do not align.

  • Confirm with BGM if readings do not match symptoms.
  • For hydroxyurea, follow device guidance and avoid relying on CGM alone.
MRI/CT/X-ray: remove Diathermy: avoid
Details
  • Remove sensor/transmitter before imaging per device guidance.
  • Do not use during diathermy therapy.
FreeStyle Libre 2
isCGM Glucose oxidase 		Vitamin C (high dose) Salicylates
Details
  • Vitamin C: higher doses may falsely elevate sensor glucose.
  • Salicylates: may reduce sensor glucose in some situations (device/label specific).

Confirm with BGM if readings do not match symptoms.

  • Ask about supplements (especially vitamin C).
  • Use BGM when values seem discordant.
MRI/CT/X-ray: remove Diathermy: avoid
Details
  • Remove sensor before imaging per device guidance.
  • Do not use during diathermy therapy.
FreeStyle Libre 3
rtCGM Glucose oxidase 		Vitamin C (high dose)
Details
  • Vitamin C: higher doses may falsely elevate sensor glucose.

Confirm with BGM if readings do not match symptoms.

  • Review supplement use.
  • Use BGM when values seem discordant.
MRI/CT/X-ray: remove Diathermy: avoid
Details
  • Remove sensor before imaging per device guidance.
  • Do not use during diathermy therapy.
Medtronic Guardian™ 4
rtCGM Glucose oxidase 		Acetaminophen (high dose)
Details
  • Acetaminophen: very high doses may falsely elevate sensor glucose.

Confirm with BGM if symptoms and sensor values do not align.

  • Ask about acetaminophen use if CGM readings seem unexpectedly high.
  • Confirm with BGM when values are discordant.
MRI/CT/X-ray: remove Diathermy: avoid
Details
  • Remove sensor/transmitter before imaging per device guidance.
  • Do not use during diathermy therapy.
Eversense E3
rtCGM Fluorescence Implantable 		Mannitol (IV) Sorbitol (IV) Tetracyclines
Details
  • Mannitol / sorbitol (IV): may falsely elevate readings.
  • Tetracyclines: may interfere with sensor fluorescence.
  • Typical dietary intake of sorbitol/mannitol does not affect readings.
  • Confirm with BGM during IV mannitol or sorbitol therapy.
  • Review antibiotics if unexplained elevations occur.
MRI/CT/X-ray: remove transmitter Diathermy: avoid
Details
  • Implanted sensor remains in place during imaging.
  • Remove the external transmitter for MRI/CT/X-ray per device guidance.
  • Do not use during diathermy therapy.
Eversense 365
rtCGM Fluorescence Implantable 		Mannitol (IV) Sorbitol (IV) Tetracyclines
Details
  • Mannitol / sorbitol (IV): may falsely elevate readings.
  • Tetracyclines: may interfere with sensor fluorescence.
  • Typical dietary intake of sorbitol/mannitol does not affect readings.
  • Confirm with BGM during IV mannitol or sorbitol therapy.
  • Review antibiotics if unexplained elevations occur.
MRI/CT/X-ray: remove transmitter Diathermy: avoid
Details
  • Implanted sensor remains in place during imaging.
  • Remove the external transmitter for MRI/CT/X-ray per device guidance.
  • Do not use during diathermy therapy.

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This site and its services do not constitute the practice of medical advice, diagnosis or treatment. Always talk to your diabetes care and education specialist or health care provider for diagnosis and treatment, including your specific medical needs. If you have or suspect that you have a medical problem or condition, please contact a qualified health care professional immediately. To find a diabetes care and education specialist near you, visit the ADCES finder tool.

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