C-Peptide Test

Submitted on March 27, 2012

This test is used to find out the amount of insulin that the pancreas of the patient is still producing, when he has been diagnosed with type 1 or 2 type of diabetes. Type 1 diabetes is actually an autoimmune process and might even start when the patient was a child. In this the beta cells get destroyed completely over time. Therefore, very less or no C-peptide is produced. This makes the patient totally dependant on exogenous insulin.

In type 2 diabetes, there is a compensatory increase in the production of insulin and an insulin resistance. This can cause beta cell damage. This kind of diabetes is treated with oral medicines that urge the body to make insulin. However, in case of beta cell damage, the patient will need injections. The C-peptide test helps to monitor the activity of beta cell. This way, the doctor knows when to begin the insulin treatment.

A C-peptide test can help find out the kind of diabetes a person has, in case it’s not clear.

C-peptide is also used to monitor the symptoms of hypoglycaemia, and administer treatment accordingly. Symptoms include seizures, fainting, blurred vision, confusion, hunger, palpitations, and sweating. This test is also done to find out why the person has hypoglycaemia.

Reasons for C-peptide test

C-peptide tests are done in order to:

  • Differentiate between type 1 and type 2 diabetes.
  • Check to see why the patient has low blood sugar.


Like most medical procedures, you may be asked to avoid drinking and eating anything for eight hours, before the blood test is conducted. If you are taking oral medicines and insulin, then you might be asked to stop taking those for sometime before the tests, as they can alter the results of the test. If you have any questions or any concerns, then consult your doctor about the same before undergoing this procedure.


This is a standard blood test, where a health care professional will clean the area, where the needle is to be inserted and wrap an elastic band to stop the blood flow from the upper arm. A tube is attached to the needle and blood is collected in the tube. It is a routine procedure and nothing you should be worried about. If done in the right way by a health care professional, then it is a simple and safe procedure.