Unexpected positive patch test reactions to sesquiterpene lactones in patients sensitized to the glucose sensor FreeStyle Libre.

ABSTRACT

BACKGROUND: Most diabetic patients sensitized to FreeStyle Libre react to isobornyl acrylate (IBOA), with a considerable number of them also showing unexpected positive patch test reactions to sesquiterpene lactone (SL) mix (SLM) tested in the baseline series. OBJECTIVES: To compile patch test results of subjects affected, and provide potential explanations for this association. PATIENTS AND METHODS: Fifty-three Freestyle Libre-allergic patients were patch tested with IBOA and/or SLM, and several were also patch tested with the components of SLM. Chromatographic analyses were performed on the glucose sensor, IBOA, and the components of SLM. RESULTS: Thirty-three patients reacted positively to the components of SLM, and 11 of 27 patients reacted positively to alantolactone, in particular. Gas chromatography-mass spectrometry (GC-MS) analyses did not detect these chemicals in the different parts of the glucose sensor, or in IBOA. CONCLUSION: Significant co-sensitizations between SLs on the one hand and the glucose sensor FreeStyle Libre and/or isobornyl acrylate on the other hand exist, without evidence of the presence of SLs via GC-MS analysis. Cross-reactions between them seem improbable. As a possible hypothesis, a common precursor for both, such as camphene, may exist.