CPT Code(s):


Collection Procedure:

Specimen: Serum

Volume: 0.8 mL

Container: Gel-barrier tube

Storage Instructions: Refrigerate.


The principal use of C-peptide is in the evaluation of hypoglycemia. Patients with insulin-secreting neoplasms have high levels of both C-peptide and endogenous insulin; in contrast, patients with factitious hypoglycemia will have low C-peptide levels in the presence of elevated (exogenous) serum insulin. C-peptide is also useful in evaluating residual beta-cell function in insulin-dependent diabetics, many of whom have antibodies that interfere with insulin assays. Glucagon-stimulated C-peptide concentration has been shown to be a good discriminator between insulin-requiring and non−insulin-requiring diabetic patients. The diagnosis of islet cell tumor is supported by elevation of C-peptide when plasma glucose is low.


Electrochemiluminescence immunoassay (ECLIA)


1 day

Reference Values:

1.1−4.4 ng/mL (Note: Reference interval is for fasting patients.)