CD02 Colophonium derivatives as key allergens in diabetes technology-associated allergic contact dermatitis: a hidden concern in the British Society for Cutaneous Allergy standard series

Abstract Continuous subcutaneous insulin infusion (CSII) and continuous glucose monitors (CGM) are integral to the management of type 1 diabetes mellitus (T1DM), improving glycaemic control and quality of life. However, allergic contact dermatitis (ACD) associated with these technologies is increasingly reported but remains underinvestigated due to the difficulty in identifying causative allergens. The British Society for Cutaneous Allergy (BSCA) standard series does not include several allergens found in medical devices, particularly colophonium derivatives, which have emerged as key allergens. The objective of this study was to identify allergens responsible for ACD in patients using CSII and CGM devices and to assess the limitations of the BSCA standard series in diagnosing device-related allergies. We studied 17 paediatric patients with adverse skin reactions to diabetes devices. All patients were patch tested with the BSCA standard series, methacrylate series and a medical device series, which included extra acrylates and colophonium derivatives. Additionally, we tested acetone extracts of six devices (Freestyle Libre 1, Freestyle Libre 2, Medtronic Guardian Sensor 3, Tandem T:slim X2, Dexcom G6 and Dexcom G7) using gas chromatography–mass spectrometry (GC-MS). The study cohort included nine male patients, aged 1–16 years. Patch tests were performed on day 0 with readings on days 4 and 7. Twelve patients tested positive for device-related allergic reactions, with nine reacting to Dexcom G7, one to Dexcom G6, and two to Tandem T:slim X2. Colophonium derivatives were identified as the primary allergens, with 10 patients testing positive to a combination of colophonium 60%, methyl hydrogenated rosinate 20% and glyceryl hydrogenated rosinate 20% in the medical device series. Only one reacted to colophonium 20% in the standard series. One reacted to hexanediol diacrylate and one to N,N-dimethylaminoethyl acrylate. Isobornyl acrylate (IBOA) was confirmed as a causative allergen, with positive reactions in two patients (one to IBOA 0.1% and 0.3%, and one to IBOA 0.3%). None reacted to 2-hydroxyethyl methacrylate in the standard series. GC-MS analysis confirmed the presence of IBOA and methyl dehydroabietate in multiple devices. In conclusion, colophonium derivatives are a key cause of ACD in patients using diabetes technology. Our findings demonstrate that the BSCA standard series may fail to identify relevant allergens in such cases, emphasizing the need for more comprehensive testing, including device-specific allergens, to improve diagnosis. GC-MS is a valuable tool but further research is required to quantify the exact contribution of these compounds. Manufacturers must be more transparent about the materials in their devices to aid diagnosis and prevent further allergic reactions.