August 26, 2001
Blood Tests and Insulin Injections
Question from Prescott, Arizona, USA:
What is the name of the test that can determine if your pancreas is producing insulin? The best I can recall is that there is a byproduct that is produced when the pancreas produces insulin versus injected synthetic insulin.
I am assuming that you have diabetes and are on insulin. In this situation, the appropriate test is the serum C-peptide level. Proinsulin in the beta cells is broken down to equimolar amounts of insulin and C-peptide. The latter can be assayed distinct from any form of insulin and for this reason it is a valid measure in a person taking exogenous insulin of how much of his/her own insulin is still being produced.