C-peptide is released in equal amounts with insulin, so it shows how much insulin your own pancreas is making.
- Normal range (adults)
- 0.8–3.5 ng/mL (0.26–1.16 nmol/L)
- Sample
- Blood
- Fasting
- Not usually needed
- Also called
- C Peptide, Connecting Peptide, Serum C-Peptide
C-Peptide normal range
| Group | ng/mLConventional units: US, South Asia | nmol/LSI units: UK, Europe, Australia, international |
|---|---|---|
| Adults | 0.8–3.5 | 0.26–1.16 |
Your report may use either unit system; labs in the Gulf often print both. Ranges also vary slightly between laboratories, so the range printed on your own report is the one to go by.
Why is the C-Peptide test done?
It helps tell type 1 from type 2 diabetes and investigate low blood sugar.
What does a high C-Peptide level mean?
High C-peptide means the pancreas is making a lot of insulin, usually because of insulin resistance.
Common causes
- Insulin resistance and type 2 diabetes
- Kidney disease
- Insulinoma (rare)
Diet and lifestyle tips
- Same as for insulin resistance: less sugar and refined carbohydrates, more fibre, regular exercise, weight loss
What does a low C-Peptide level mean?
Low C-peptide means the pancreas is making little insulin.
Common causes
- Type 1 diabetes
- Long-standing type 2 diabetes
- Pancreatic damage
Diet and lifestyle tips
- Insulin treatment is usually needed; follow your diabetes team's plan
When should you see a doctor?
Your doctor will interpret C-peptide together with your blood sugar at the time of the test.
Last updated
This page is for general education and is not a diagnosis. Normal ranges differ between laboratories, so always compare your result with the reference range printed on your own report, and discuss abnormal results with your doctor.