What is this test?
C-peptide is secreted along with its own insulin and helps estimate how much insulin the pancreas is producing.
Why might it be ordered?
- To distinguish self-produced insulin from exogenously administered insulin.
- When evaluating unexplained low blood sugar or to clarify diabetes and residual pancreatic function.
What sample is needed?
A healthcare professional collects a venous blood sample. Depending on the method, the laboratory uses serum or plasma.
How should you prepare?
Depending on the purpose, the sample may be collected while fasting or after stimulation. Follow the assigned protocol and report insulin and other diabetes medicines. Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
The result is interpreted with blood glucose and kidney function. On its own, it cannot determine the type of diabetes or the treatment needed. Your result is interpreted using the reference interval on the laboratory report and in the context of your symptoms, medical history and other test findings.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.