INS and type 1 diabetes mellitus: These results: (i) provide further independent biological confirmation of the original T1D–MVPs (in addition to the 4 different T1D–discordant MZ pairs described above); (ii) demonstrate that T1D–MVPs precede clinical diagnosis; (iii) and show that T1D–MVPs can be identified in the context of normoglycaemia, independent of the disease process, metabolic dysfunction, pharmacological or insulin treatment, or the twinning event since the replication was performed in singletons.