C-peptide measured after a standard meal (fasting and postprandial)
This test helps assess how well your pancreas produces insulin after eating. It measures C-peptide levels before and after a meal to check insulin function.
["A key way to evaluate your pancreas’s insulin production after meals."]
Key facts at a glance
- LOINC
- 95087-3
- Short code
- C peptide 3h p meal SerPl-mCnc
- Synonyms
- C peptide 3h p meal 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 This Test Is Done
Your doctor may order this test if you have symptoms like unexplained weight loss, fatigue, or signs of diabetes (such as frequent urination or thirst). It can also help diagnose or monitor conditions like type 1 or type 2 diabetes, or pancreatic issues. This meal-based test helps doctors see how your body responds to food, which is important for managing insulin production over time.
What to Expect Before the Test
You’ll fast for about 8–12 hours before the test, then eat a specific meal provided by the lab. Blood samples are taken before the meal (fasting) and at intervals afterward to measure C-peptide levels. This helps track how your pancreas releases insulin naturally.
What Happens During the Test
Blood is drawn from a vein (usually in your arm) at set times—once before eating and then at intervals (e.g., 30 minutes, 1 hour, 2 hours) after finishing the meal. The lab analyzes the samples to measure C-peptide, a marker of insulin production.
What the Results Mean
Results compare your C-peptide levels before and after eating. Low or fluctuating levels may indicate problems with insulin production, while normal patterns suggest healthy pancreatic function. Your doctor will interpret these results in the context of your symptoms and medical history.
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 meal tolerance test
Frequently asked questions
How long does fasting last before the test?
Will I feel different after eating the meal?
Can I take my diabetes medications on the day of the 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