C-peptide (Serum) with 15-Minute Postprandial Glucose Measurement
This test measures C-peptide, a natural byproduct of insulin production, alongside blood glucose levels taken 15 minutes after eating. It helps assess how your pancreas responds to food.
["This test helps track how your body produces insulin after meals and may support diabetes management."]
Key facts at a glance
- LOINC
- 47585-5
- Short code
- C peptide 15M p Glc SerPl-sCnc
- Synonyms
- C peptide 15M p Glc SerPl-sCnc
- Category
- glucose
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- true
- 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 diabetes or are at risk for it to evaluate how well your pancreas produces insulin. It can also help monitor how well your current diabetes treatment is working, especially after meals.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, typically drawn from a vein in your arm. If glucose is measured postprandially, you may be asked to eat a small meal or snack before the blood draw.
What the Results Mean
C-peptide levels help determine if your pancreas is producing insulin normally. Elevated glucose levels after eating may indicate poor insulin function or resistance. Your doctor will interpret these results in the context of your overall health.
Common Causes of Abnormal Results
Low C-peptide levels might suggest insulin overproduction (e.g., from a tumor) or inadequate pancreatic function. High glucose levels after eating could indicate diabetes, metabolic syndrome, or poor meal management.
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.
This test is critical for diagnosing and managing type 1 and type 2 diabetes, particularly in assessing insulin secretion dynamics. It can also help differentiate between insulin-dependent and insulin-independent conditions, such as gestational diabetes or pancreatic disorders.
Short name
C-peptide + Glucose Check
Frequently asked questions
Will I need to fast before this test?
How long will it take to get my results?
Can I take my diabetes medication before 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