The challenge is to be selective, to avoid global immune suppression; and non-invasive, to intervene as early as possible in children at risk of developing type 1 diabetes. We have devised a novel vaccine using Fc-fused preproinsulin (PPI-Fc) that meets these criteria, and we are currently exploring its therapeutic efficacy for T1D prevention using the oral (Corcos et al. Front Immunol 2021) or intranasal route. We are also testing the efficacy of PPI-Fc in another indication, insulin allergy, which is a rare but severe complication of insulin therapy in diabetic patients.