C-peptide (Serum/Plasma) Quantitative Measurement
This test measures the amount of C-peptide, a small protein produced naturally in the pancreas along with insulin during digestion. It helps assess how well your pancreas is producing insulin.
["C-peptide helps doctors check insulin production and rule out diabetes-related issues."]
Key facts at a glance
- LOINC
- 58501-8
- Short code
- C peptide 15M pre chal SerPl-mCnc
- Synonyms
- C peptide 15M pre chal SerPl-mCnc
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test to evaluate your pancreas’s ability to produce insulin. It can help diagnose diabetes, monitor insulin production in people with diabetes, or investigate symptoms like unexplained weight loss, fatigue, or high blood sugar levels. C-peptide levels are also used to distinguish between insulin-dependent and insulin-independent causes of low blood sugar.
What to Expect Before the Test
No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other blood tests. If you’re on insulin or certain medications, let your doctor know before the test.
What the Results Mean
C-peptide levels help determine whether your body produces insulin naturally. Low levels may indicate insulin deficiency, while normal or high levels can help confirm diabetes or rule out other conditions. Your doctor will interpret results in the context of your symptoms and medical history.
Common Reasons for Testing
Doctors use C-peptide testing to diagnose diabetes (especially Type 1), check insulin production in people with diabetes, or investigate unexplained symptoms like fatigue, weight changes, or recurrent infections. It can also help distinguish between diabetes and other conditions that affect blood sugar.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: C-peptide is a biomarker for pancreatic beta-cell function. Low levels suggest insulin deficiency, which may require treatment like insulin therapy. Elevated levels can indicate overproduction of insulin (e.g., in rare syndromes) or may be seen in some metabolic disorders. This test is particularly useful in diagnosing Type 1 diabetes, where insulin production is severely reduced, and distinguishing it from Type 2 diabetes, where insulin production may still be present.
Short name
C-peptide level
Frequently asked questions
What does a C-peptide test tell me about my diabetes?
Can I eat or drink before this test?
How long will I need to wait for my results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy