C-peptide results help


I cash purchased c-peptide along with GAD, IA-2 and insulin autoantibodies. The c-peptide (fasting) results came back this evening, the rest are pending. Can I please get some insights from the experts? Thank you in advance.

C-peptide 1.08 ng/ml
Range 0.80 - 3.85

Superficially, that’s in the normal range. But c-peptide really only tells you something with additional information. How long have you been diabetic? Did you have a high blood sugar at the same time (i.e., same blood draw) as your C-peptide test?

It really only tells you how much insulin your body is making. You need other information to be able to interpret it meaningfully.

Hello David,

Technically, I’ve only been diagnosed with GD with my pregnancy that ended 3 years ago. When my son was about 6-8 months my problems appeared to return. I’ve been on a roller coaster since with my sugars and the medical providers I’ve seen. Hence why I’m paying cash for these tests. It’s a long story, that has been dismissed and glazed over despite moderate-high sugars, high ketones in my urine, 30-40 lb weight loss and eye health changes, including Migraine with auras, and other diagnoses. So I’m not diagnosed as diabetic at this time, I’m trying to document what I can to either support a diagnosis, or in the least help convince a provider to submit additional testing.

This c-peptide draw was while fasting (approx 10hrs), I am unsure of my BS at the time and did not include that value with my other testing- nor did I bring my glucose monitor with me.
I did not limit my intake for any “days” leading up - actually my Sons Birthday was 2 days before, and I consumed 70% of a cupcake along with some bbq food which I later regretted for the next 1/2 day. Anywho, I don’t know if I answered your question. But in the least I gave some insight.

I thank you for your reply. I’ll post the other results when they come if they are question inducing.

@alegna242 I’m not sure if its consider inappropriate but do you mind sharing how much those test cost out of pocket?

I’ve been asking my doctor to re-run my GAD and I-A2 and they won’t. I’m curious what it cost to do my self.

For what its worth when I was diagnosed LADA my c-peptide was .92 (normal). I’m suppose to get retested in January and hoping to see at least a similar number.

Now that I am on an insulin pump, my C-peptide usually comes in at 0.01. When my A1c was in the 10 range, my C-peptide was up to 0.2. Apparently, when your pancreas is under stress, it does produce some insulin.

When you’re injecting insulin, your body doesn’t need to make it, so it doesn’t produce much and a C-peptide doesn’t tell you much.

What this test tells Alegna is that she isn’t insulin resistant (IR people would be closer to 3).

Hello Chris,

Absolutely I’ll share! If it helps you or anyone it would be an honor to do so. The site is called Ulta Lab tests. You can choose either any Quest lab or Lab Corp locations which is extremely convenient and quick. As you can see I also obtained a 20% discount which I earned after I choose over $200 in services. They also have “sales” on certain tests from time to time. I suggest googling for codes or just searching their current “specials” on the site. This is the second time I’ve used them and it’s been a pleasure.

Hope this helps!

Thank you for your reply. I appreciate the insight. Hoping for some more answers soon.

Good to know. Question, do you know if your stated values were in nmol/L or ng/mL?

Thank you in advance.

Thank you for sharing. I looked t the site and the test are much cheaper then I would have guessed. I think in the future I might be using this to answer my own questions when the doctor does not agree with what I want to keep tabs on.

Exactly in the same situation as you. I am grateful we have an option to empower ourselves.

Good luck.

My GAD came back today. I’m confused. <5? No specific values? Some literature is even more confusing stating numbers well below 5 are indicative of positive value? Help?

Thank you in advance.

Wow just what i have been looking for! Not for these tests, but I would love to get more thorough thyroid tests since my doctors all refuse to actually do anything more than TSH and total (or maybe it is free?) T4. I asked for more tests be done last time I was at my endo and he basically said no one believes any of the other tests matter…a little simplistic for complex bodily processes…

It is possible that <5 is the lowest result that this lab test is sensitive enough for. And I would interpret your result as saying that you do not have those antibodies.


Interesting results. I don’t have many answers for you, but I’ll tell you that your not alone. I’ll give you some insight on my numbers. My C-Peptide came back at 1.89 (my BG was 136 at the time). My insulin came back at 10.9 and no anti-bodies present. I was told that it would have been more important to test the C-Peptide under stress? I’m starting to think that the tests don’t actually mean much. I hope you find some answers. (And post them…lol).

I don’t know that this will help you but a few months after my diagnosis I had the C-peptide test done. I was fasting at the time of the test because the lab said the test was more accurate when fasting. My test showed my level was .2 with the normal range being .8 - 3.5, and my blood sugar at the time was in the normal range. My doctor said that my .2 level indicated virtually no production of insulin.

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