INS and type 1 diabetes mellitus: (Pre-)proinsulin ([P]PI), glutamic acid decarboxylase (GAD), the tyrosine phosphatase IA-2, and the zinc transporter ZnT8 play a particularly prominent role and are recognized by autoantibodies detected in routine clinical laboratory assays (see5,6 for a discussion of the role of B lymphocytes and autoantibodies in T1D).