Hi, the point of the c-pep is to discovery how much insulin you produce naturally, if your sugars are reasonably high after food, you should be showing some if you make some.
I purposely didn’t take my insulin, I also took the test as an ideal excuse to eat a McDonald’s breakfast lol, I figured without injected insulin, my body should make more, but that was just my theory. Probly should just follow the rules, have something nice that you miss.
good luck, I hope you get the result you are hoping for.