C-Peptide · high result
What does a high C-Peptide mean?
Short answer
C-peptide is released with insulin, so a high level means the pancreas is making a lot of insulin — insulin resistance and early type 2 diabetes, obesity, PCOS, some medications, or reduced clearance in kidney disease. Very high values with low glucose raise the question of an insulinoma or sulfonylurea use. Unlike insulin assays, C-peptide is unaffected by injected insulin.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
What is the normal range for C-Peptide?
- age 18+: 1.10 – 4.40 ng/mL
Full reference table, citations and testing options: C-Peptide biomarker page.
What are the common causes of high C-Peptide?
- Insulin resistance, prediabetes, early type 2 diabetes
- Obesity, PCOS, metabolic syndrome
- Sulfonylurea or meglitinide medication
- Chronic kidney disease (slower clearance)
- Insulinoma (rare; with hypoglycemia)
What symptoms go with high C-Peptide?
- Often none
- Weight gain around the middle, hunger, afternoon crashes
- Sweating, shakiness, confusion if glucose is low
What do clinicians usually check next?
- Fasting glucose and A1c drawn at the same time
- Kidney function
- If glucose is low: supervised fasting evaluation for insulinoma
Follow-up tests available at TestWell: Glucose ($14.99).
How do you recheck C-Peptide?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Pre-Diabetes Panel | Panel · 5 tests | $89.99 | Yes | 2–5 business days |
| Total Body Panel | Panel · 49 tests | $499.99 | Yes | 5–10 business days |
| C-Peptide | Test | $29.99 | Yes | 2–4 business days |
Common questions
Why test C-peptide instead of insulin?
It lasts longer in the blood, is not confused by injected insulin, and reflects the pancreas's own output — useful for telling type 1 from type 2 and for insulinoma work-ups.
Sources
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.