to investigate whether the unexpectedly high c-peptide levels in some insulin-dependent diabetic ( iddm ) patients are due to co-determination of proinsulin bound to circulating insulin antibodies , 36 randomly selected sera from iddm patients were assayed for c-peptide immunoreactivity ( cpr ) after polyethylene glycol ( peg ) extraction , preceding incubation with proinsulin binding antibodies ( lab + peg ) or without pretreatment of the sera .
C0006558
c-peptide
C0033362
proinsulin