Question about C-peptide result.

By Andrea7777 Latest Reply 2013-09-14 03:13:22 -0500
Started 2013-09-12 11:32:11 -0500


i am T2 (well diagnosed as non insulin dependant diabetic) and i have had my C-peptide also tested. I can only go with my results to the doctor in October…and what i am wondering, if my C-peptide is too low? I am on oral medication now. Thank you for your reply

my fasting BG is now 96 mg/dl
insuline: 2,43 mIU/l
Hemoglobine A1c%: 3,86 %
C-peptide: 0,71 ng/ml (there is a "-" between it and written that the reference would be between: 0,78-5,19)

2 replies

Andrea7777 2013-09-14 03:13:22 -0500 Report

Thank you John and Type1Lou for your replies! :)
What is strange that i was very insuline resistance like 1 year ago (i had on my paper also written "hyperinsulinemia") after my 2 hour OGTT test back then i had a very high insuline level (200 mIU/l) and that would sugget for my C-peptide to be high now (because of the insuline resistance). so strange a bit.
Thank you for the tip for asking an expert here, i will do, and i will also let you know what my doctor said in October! :)

Type1Lou 2013-09-13 13:00:15 -0500 Report

It is my understanding that a C-peptide test is done to determine whether any insulin is being produced at all. If no insulin is produced, you are diagnosed as a type 1 and must take insulin. Generally, Type 2's produce some insulin but diabetes results either because not enough insulin is being produced or because there is insulin resistance. As John Crowley noted, your results were in the low normal range and your A1c appears excellent. This is a question you may wish to direct to one of the experts…see the "Ask an expert" tab in the blue line at the top of this page.

John Crowley
John Crowley 2013-09-13 12:30:05 -0500 Report

Hi, Andrea.
From what I was able to look up (here:;) it appears that the normal range for c-peptide is 0.5 to 2.0 ng/mL.

Your reading of 0.71 would be at the low end, but still within normal range.

Definitely something to discuss with your doctor. For many people with type 2 diabetes, their c-peptide is high because of insulin resistance. But I'm not sure how that might be influenced by the oral meds you're taking.

Good luck with everything. Let us know how it goes and what you learn.