C-peptide (Serum/Plasma) with 15-minute postprandial collection
This test measures C-peptide, a natural byproduct of insulin production, to help assess how your pancreas is making insulin, especially after eating.
["C-peptide helps evaluate insulin function and rule out insulin misuse or excess insulin production."]
Key facts at a glance
- LOINC
- 77610-4
- Short code
- C peptide 15M p chal SerPl-sCnc
- Synonyms
- C peptide 15M p chal SerPl-sCnc
- 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 This Test Is Done
Doctors may order this test to check if your pancreas is producing enough insulin naturally. It can also help diagnose conditions like diabetes, insulinoma (a rare tumor that causes too much insulin), or other metabolic disorders. The 15-minute postprandial (after-meal) sample helps see how your body responds to food.
What to Expect Before the Test
You’ll fast for about 8–12 hours before your blood is drawn, but you can drink water. The test involves a simple blood draw from a vein, usually in your arm. The 15-minute sample is taken shortly after you eat a small meal.
What the Results Mean
C-peptide levels help determine whether your insulin production is normal or abnormal. High levels might suggest overproduction of insulin, while low levels could indicate insufficient insulin or other metabolic issues. Your doctor will compare these results with your medical history and other tests.
Common Conditions This Test Helps Diagnose
This test is particularly useful for diagnosing insulin-related disorders, such as type 1 or type 2 diabetes, insulinoma, or pseudohypoglycemia (false low blood sugar). It can also help distinguish between insulin-dependent and naturally produced insulin in people with unexplained symptoms.
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
Short name
C-peptide (Post-Meal)
Frequently asked questions
How long does it take to get results from this test?
Can I eat before the 15-minute postprandial sample?
Is fasting required for this test?
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