C-peptide blood test
Quick answer: A C-peptide test measures a substance released with insulin, showing how much insulin your own pancreas is making. Doctors order it to help tell type 1 from type 2 diabetes, or to look into low blood sugar episodes.
- SampleBlood
- TakesAbout 5 minutes
- Before the testYour doctor may ask you to fast; follow the instructions given.
How the test is done
- 1You may be asked to fast, or to come after a meal, as instructed
- 2A needle draws blood from a vein
- 3Blood glucose is often measured at the same time
- 4The lab measures C-peptide
What your results can mean
Reading your report
Normal ranges differ between labs and by age and sex, so discuss your result with your doctor.
If the result is outside the usual range
A low level can be seen with type 1 diabetes or long-standing diabetes where the pancreas makes little insulin. A high level can be seen with insulin resistance, type 2 diabetes, kidney disease or, rarely, an insulin-making tumour.
Who usually has this test
People with diabetes where the type is unclear, and people with unexplained low blood sugar episodes.
Risks and aftercare
If you fasted, eat once the sample is taken; a small bruise may appear.
Names and options
Also called: C peptide
Listed by the hospital as
- C-PEPTIDE, SERUM
Questions about this test
How is C-peptide different from insulin?
C-peptide is released in equal amounts with insulin made by your pancreas. Unlike insulin, it is not affected by insulin injections.
Can C-peptide tell type 1 from type 2 diabetes?
It can help. People with type 1 diabetes usually make little C-peptide, while people with type 2 often make normal or high amounts.
Why is glucose measured at the same time?
C-peptide depends on blood sugar. Knowing your glucose helps your doctor read the result.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
Reception
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.