FreeStyle Libre 3 Plus Sensor Components and Allergen Information
Key Allergen Identified in FreeStyle Libre Sensors
The FreeStyle Libre glucose sensor contains isobornyl acrylate (IBOA) in its adhesive component, which has been identified as the primary culprit allergen causing allergic contact dermatitis in users. 1
Chemical Composition Details
Primary Allergen
- Isobornyl acrylate (IBOA) is present in the adhesive patch of the FreeStyle Libre sensor, confirmed by gas chromatography-mass spectrometry (GC-MS) analysis 1, 2
- IBOA has caused numerous cases of allergic contact dermatitis, with 12 out of 15 tested patients showing sensitization to this specific acrylate 1
Additional Sensitizing Component
- N,N-dimethylacrylamide (DMAA) has been identified as a second sensitizer in the FreeStyle Libre sensor through GC-MS analysis 3
- Six out of seven tested patients reacted to both IBOA and DMAA, while one patient reacted only to DMAA 3
- DMAA was found in extracts of both the adhesive patch and the sensor itself 3
Sensor Technology Components
Glucose Detection Chemistry
- The FreeStyle Libre uses wired glucose oxidase (GO)-based enzyme technology with a sensing membrane 4
- The sensor operates at very low voltage, which reduces susceptibility to electrochemical interferent substances 4
- An osmium (Os)-based mediator molecule is incorporated into earlier Abbott sensor constructs (FreeStyle Navigator) to reduce oxygen dependency 4
Clinical Implications and Interferences
Known Chemical Interferences
- Salicylic acid and ascorbic acid can affect sensor accuracy by reacting with the sensor's electrode 4
- Acetaminophen (paracetamol) at high doses (>4 g per day) may interfere with glucose readings 4
- The wired-enzyme technology with sensing membrane has been shown NOT to be susceptible to acetaminophen at therapeutic levels 4
Important Caveat for Dialysis Patients
- Icodextrin, a component of peritoneal dialysis solutions, may potentially interfere with the sensor, though specific studies are lacking 4
- GO-based sensors like FreeStyle Libre should NOT be used in patients receiving peritoneal dialysis due to potential interference 4
Alternative Options for Allergic Patients
Patients who develop IBOA allergy from FreeStyle Libre can use the Dexcom sensor as an IBOA-free alternative. 5
- GC-MS analysis confirmed the Dexcom sensor is IBOA-free 5
- All five tested patients with IBOA allergy tolerated the Dexcom sensor for at least 2 days without skin reactions 5
- The Medtronic Enlite sensor and Paradigm MiniMed Quick-set insulin infusion set also contain IBOA and are NOT suitable alternatives for IBOA-sensitized patients 6