In an effort to develop a highly specific and reliable assay for proinsulin proteoforms in T1D research, TaMADOR has developed a prototype LC-MS/MS assay targeting surrogate peptides unique to each of the 4 proinsulin proteoforms (C-peptide, intact proinsulin, des-31,32, and des-64,65 proinsulin). This evidence concerns the gene INS and type 1 diabetes mellitus.