Test Name: C-Peptide
Formal Name: C-Peptide
Other Names: Connecting Peptide, C-peptide
Normal: 0.5-2.0 ng/mL. High: Insulin resistance (Type 2), insulinoma. Low: Type 1 diabetes or advanced pancreatic failure.
Why Test: To distinguish between Type 1 and Type 2 diabetes and assess insulin production.
When to Test: New diabetes diagnosis, monitoring pancreatic function, or insulinoma.
Test Principle: Immunoassay.
Q1: Why not just measure insulin? A1: Insulin is cleared by the liver quickly; C-peptide lasts longer and reflects true production better. Q2: Does this tell me if I need insulin? A1: If low, you likely need insulin replacement.
