Were you fasting at the time, and if so what was your FBG as shown on those results?
Here's a website that will sort of answer your question:
An Old Test Teaches Doctors New Tricks—C-peptide Exam Becoming an Accepted Tool for Diabetes Treatment - Diabetes Health
In there it states this: A consistent display of high blood glucose levels may be sufficient proof of diabetes, but elevated C-peptide levels may reveal if the body has grown resistant to the insulin it is producing. Low or absent C-peptide levels may indicate that insulin production is diminished or non-existent. Anything below the normal range of 0.5 to 3.0 ng/ml of blood means that insulin production has slowed down abnormally, and generally indicates type 1 diabetes. Type 2s, on the other hand, will often yield C-peptide results in the normal range, meaning their fluctuating blood sugars must be due to insulin resistance, rather than decreased production.
I saw once, a chart that showed the criteria for c-peptide/fbg levels to accurately diagnose Types 1, 1.5, or 2. I can't seem to find that one again, I'll keep looking.
