Evaluation and Clinical Significance of Four Different Immunoassays in Detection of Serum C-peptide

To analysis the discrepancy among four different C-peptide immunoassay methods and to study their impact on the clinical evaluation of islet β cell secretory function of diabetic patients. 152 serum samples which were from 51 patients consisting of 13 with normal glucose tolerance, 8 with impaired fasting glucose, 9 with impaired glucose tolerance and the rest 21 with type 2 diabetes were involved in this study. The serum C-peptide levels in samples were measured simultaneously by radioimmunoassay, two-type chemiluminescence immunoassays and electrochemiluminescence immunoassay. The results showed that the serum C-peptide levels varied significantly from one assay method to the other (P<0.0001) though the correlation coefficients between different assays were from 0.74 to 0.99. Meanwhile, the magnitude of serum C-peptide dynamic patterns was almost identical, thus making no significant variance for the evaluation of islet β cell function. (authors)