P4HB and type 1 diabetes mellitus: In a small population of early onset T1D patients (n=21, under 1 year of disease duration), we found that 76% patients had either anti-PDIA1/P4Hb alone (11 out of 21 patients) or anti-PDIA1/P4Hb linked with anti-insulin (auto)antibodies (5 out of 21 patients).