C-peptide (Serum) Quantitative

What Is C-Peptide Used For?

C-peptide is primarily used to evaluate pancreatic function. It helps distinguish between conditions where insulin is produced naturally versus when it is injected or supplemented. For example, it can help identify whether diabetes is caused by insufficient insulin production (type 1 or type 2 diabetes) or other factors like insulin resistance or external insulin use.

Why Might You Need This Test?

Your doctor may order a C-peptide test if you have diabetes symptoms, unexplained blood sugar issues, or if they suspect a problem with how your pancreas produces insulin. It can also be used to monitor treatment effectiveness or rule out conditions like insulinoma (a rare tumor that causes excessive insulin production).

How Is the Test Done?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it is analyzed to measure the concentration of C-peptide. This test does not require fasting, but your doctor may provide specific instructions.

What Does the Test Result Mean?

Results are interpreted based on your clinical picture rather than a single reference range. High levels may suggest overproduction of insulin (e.g., insulinoma) or recent insulin administration, while low levels may indicate insufficient pancreatic function. Your doctor will discuss findings in the context of your health.