Quick highlights
- Reflects endogenous insulin production (released with insulin)
- Useful in distinguishing insulin deficiency vs resistance patterns in selected cases
- Interpretation depends on glucose level at the time of sampling
- Fasting vs stimulated protocols vary by clinical question
- Medication timing (insulin/secretagogues) can affect results
- Often paired with glucose and HbA1c for context
- Not a standalone diabetes diagnosis tool
- Home blood collection available in many service areas
- Clear safety guidance for hypoglycemia symptoms
- SEO coverage: C-peptide test, insulin production blood test, diabetes type test support
What’s included
Preparation
- Follow clinician instructions for fasting vs non-fasting protocol
- If fasting advised, fast for the specified hours (water allowed)
- Do not change insulin/diabetes medicines unless clinician instructs
- Note the time of last meal and medicine dose for accurate interpretation
- Collect serum blood sample via trained phlebotomist
- If ordered, get glucose tested at the same time
- Download report from <a href='/my-account/'>View reports</a>
- Review with endocrinologist/diabetologist for next steps
FAQs
A molecule released with insulin when your pancreas produces insulin; it reflects endogenous insulin secretion.
It depends on the protocol; follow clinician instructions.
Because interpretation depends on blood glucose level at the time of sampling.
Injected insulin does not contain C-peptide, but therapy can affect physiology; disclose your regimen.
Yes, especially medicines that increase insulin secretion; disclose timing and doses.
It can support clinician assessment of insulin production context, but diagnosis is clinical and may include antibodies and history.
Not always; interpretation depends on context, duration of diabetes, and glucose levels.
Yes, in clinician-supervised workups of low sugar episodes.
Often same day or within 24 hours.
Serum blood sample.
Yes in many serviceable areas.
Follow clinician guidance; do not make major changes unless advised.
Download from <a href='/my-account/'>View reports</a>.
Treat symptoms per your clinician’s plan and seek medical help if severe.
Notes
C-peptide interpretation depends on glucose and insulin status.
