C-peptide is produced in the pancreas and helps to stimulate insulin production. It also acts to decrease high glucose-induced ICAM and VCAM, which may be associated with atherosclerotic heart disease.
When you eat, your body releases proinsulin into the bloodstream, which is then converted by the beta cells of the pancreas to insulin and C-peptide. Equimolar amounts of these molecules are then stored in the secretory granules of the beta cells, and they are released to the portal circulation when there is need for them to transport glucose into cells where it can be used as energy.
In people with diabetes, their beta cells can no longer make enough insulin to meet their needs. Usually, the body uses a small amount of exogenous insulin to replace what it has lost.
A C-peptide test can help to identify and classify Type 1 or Type 2 diabetes. It may also be helpful to know how well diabetes treatment is working.
The test is usually done with a blood sample. A nurse or doctor at your doctor’s office, health clinic, hospital, or lab will draw a blood sample from a vein in your arm. You may feel a slight prick as the needle is inserted.
Depending on your provider, you might need to fast (not eat or drink) for eight to 12 hours before the test. You might need to stop taking some medications, including vitamin B7 or Biotin, at least 72 hours before the test.