C-Peptide levels: what's normal, high and low
A byproduct of insulin production. Reflects how much insulin your pancreas is making, not how much you've injected.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
The short answer
C-Peptide is measured with a standard blood draw after an 8–12 hour fast. A typical reference range is 1.10 – 4.40 ng/mL. At TestWell it's $29.99 all-in as C-Peptide, results in 2–4 business days, drawn at Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.
- Units
- ng/mL
- Sample
- Blood draw
- Fasting
- 8–12 hours
- Results
- 2–4 business days
- Price
- $29.99
- Labs
- Labcorp
C-Peptide Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+ | 1.10 – 4.40 ng/mL |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
How do you get a C-Peptide test?
Order online, a licensed physician reviews the requisition, and you walk into a nearby lab for the draw. C-Peptide is available on its own or inside these panels — panels cost less per marker when you want the fuller picture.
| Option | Includes | Price |
|---|---|---|
| C-Peptide | This marker only | $29.99 |
| Pre-Diabetes Panel | 5 tests | $89.99 |
| Total Body Panel | 49 tests | $499.99 |
Quest vs. Labcorp for C-Peptide: which lab should you pick?
Both are CLIA-certified national labs and the result is clinically equivalent, so pick whichever location is closer. Your report will print that lab's own reference range, which can differ slightly from the table above.
| Lab | Available | Price |
|---|---|---|
| Quest Diagnostics | No | — |
| Labcorp | Yes | $29.99 |
| BioReference (NY & NJ) | No | — |
Need help choosing a location? Use the lab finder to see draw sites near your ZIP.
Related Diabetes & Blood Sugar biomarkers
Markers commonly tested alongside C-Peptide.
Frequently asked
No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor.
Ready to test your c-peptide?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $29.99.