I’ve had type 1 diabetes for about 23 years, I’ve been on a pump for about five months, and I have never had a C-peptide test. Previously, I ordered pump supplies with no problem, but when I ordered more a few days ago, my doctor’s office called me and told me that the pump company says I need to have a C-peptide test done.

How long has the C-peptide test been around? Should my doctor, an endocrinologist, have ordered this test before now?

Your insurance company is really driving this. Many are now saying that they will limit reimbursement for insulin pumps and supplies to only those with type 1 diabetes. So, the pump supply company is acting on instruction/guidance from your insurance company. Using the C-peptide is one way of demonstrating you have no insulin secretion.

The C-peptide test has been around since 1980. Usually, when a person has type 1 diabetes, the C-peptide should be unmeasurable to very low. If the C-peptide is not low, this might be consistent with type 2 diabetes, and it gets the insurance company out of having to provide supplies for a condition they won’t cover. This is an oversimplification of the situation. However, if this has not been done, you might as well get the C-peptide, and then it will be on the record.

It is not improper medicine to not have had had a C-peptide in the past. Previously, this was more of an academic test.

JTL