N,N-dimethylacrylamide - a new sensitizer in the FreeStyle Libre glucose sensor.

Background: Isobornyl acrylate (IBOA) has recently been identified as one sensitizer in the FreeStyle Libre glucose sensor. Analyses with gas chromatography-mass spectrometry (GC-MS) have indicated the presence of N, N-dimethylacrylamide (DMAA) in the sensor. Material and methods: Seven patients were referred for patch testing after developing skin reactions when using FreeStyle Libre. All patients were patch tested with IBOA and DMAA. Two patients were tested with adhesive patches that had been removed from the sensors " as is," and two patients were tested with acetone extracts of materials from the sensor. The extracts were analysed with GC-MS. Results: Six patients reacted to both IBOA and DMAA, and one patient reacted only to DMAA. Positive reactions were also observed in both patients tested with the adhesive patch " as is". One patient reacted to both an extract of the adhesive patch and an extract of the sensor itself. When analysed with GC-MS, IBOA was found in both extracts and DMAA was found in the extract of the sensor. Conclusion: Both IBOA and DMAA may be present in adhesives used in medical devices such as glucose sensors or insulin pumps, and should be patch tested when suspected contact allergic reactions to these products are investigated.