C-Peptide
C-peptide is released one-to-one with insulin when proinsulin is cleaved in pancreatic beta cells, so it measures endogenous insulin production even in people receiving insulin therapy. Low values suggest type 1 diabetes or advanced beta cell failure, while elevated values accompany insulin resistance, type 2 diabetes, or insulinoma.
Optimal range: who says what
No institution or named practitioner we track states an optimal target for C-Peptide. How we verify ranges.
- No stated targetNo separate optimal establishedRead alongside fasting glucose and insulin; it reflects how much insulin the pancreas makes
- Lab reference interval0.5-2.0 ng/mLWhat a lab report flags against. A lab interval is not an optimal target.
2 providers include this
Metabolic Health / Glucose
Why C-Peptide matters
Measures how much insulin your pancreas produces. Unlike insulin tests, not affected by insulin injections. Distinguishes Type 1 from Type 2 diabetes. Indicates beta cell function.
Which Providers Test C-Peptide?
Function Health is both the cheapest ($365/year) and the most comprehensive (160+ biomarkers) panel that includes C-Peptide.
2 panels that include it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
 Function Health | $365 | 160+ | $2.28 |
| $700 | 138 | $5.07 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
19 itemized panels do not include C-Peptide
Superpower · WHOOP Advanced Labs · Labcorp OnDemand · Life Extension Elite · Everlywell · Mito Health · InsideTracker · Marek Health Base · Marek Health Comprehensive · Marek Health Complete · Marek Health Executive · Blueprint · Empirical Health · Oura Health Panels · SiPhox Health · Hims Labs · Healthspan · Vitality Blueprint Standard · Ultrahuman Blood Vision Annual
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer C-Peptide. Check with them directly.
Life Extension Standard · Quest Health · Ultrahuman Blood Vision · Lifeforce · Hundred Health · Personalabs · Walk-In Lab · HealthLabs · WHOOP Specialized Panels · Marek Health Essential · Vitality Blueprint Upload
Frequently Asked Questions
What is the optimal range for C-Peptide?
No separate optimal established: Read alongside fasting glucose and insulin; it reflects how much insulin the pancreas makes. Lab reference interval: 0.5-2.0 ng/mL. That is what a lab report flags against, not an optimal target.
Which blood test providers include C-Peptide?
2 of the 21 blood testing panels we itemize marker by marker include C-Peptide in their panels. This biomarker has limited availability.
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Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Sep 23, 2026 · First published Nov 30, 2025