Test Code 410
Test Details
C-Peptide
Connecting Peptide (C-peptide) is a polypeptide produced by β-cells of the pancreas along with insulin. It serves as an accurate measure of insulin production, even in patients receiving insulin treatment.
Methodology
Electrochemiluminescence immunoassay
Patient Preparation
None
Preferred Specimen
1.0 mL serum (0.5 mL minimum) collected in serum separator tube (SST / Tiger Top)
Alternate Specimen
1.0 mL (minimum) plasma collected in EDTA plasma separator tube (Pearl Top)
Transport Temperature
Refrigerated (ship on frozen cold packs)
Stability
Refrigerated: 3 days
Lab Values
C-Peptide
Non-Diabetic
- Optimal: <3.0 ng/mL
- Borderline: 3.0 – 4.0 ng/mL
- Increased Risk: >4.0 ng/mL
Diabetic
- Borderline: 2.0 – 4.0 ng/mL
- Increased Risk: <2.0 or >4.0 ng/mL
Clinical Significance
C-Peptide
Elevated C-peptide levels associated with:
- hyperinsulinemia
- insulin resistance
- obesity
- renal insufficiency
Decreased C-peptide levels associated with:
- insulin deficiency
- starvation
- hypoglycemia
- Addison’s disease
- post pancreatectomy
- High doses of biotin (> 5 mg/day) may interfere with assay results. Patient assumed to be refraining from biotin supplementation for at least 3 days prior to blood draw.
Treatment Options
C-Peptide
- Insulin treatment for diabetic patients with low levels.
- Lifestyle modification and other agents for diabetic patients with normal or elevated levels.
