Update on clinical trial, c-peptide results

I got good news from my lab results from last week!!

First of all, my a1c went down to 5.5 from 5.8. I tested negative for Celiac’s disease and my thyroid is still functioning, despite my positive antibodies. I wanted to get my thiamine levels tested and my endo said okay but for some reason they didn’t get the results back from that…

The clinical trial I’m in is testing abatacept, a drug that could possibly prolong the honeymoon phase in newly onset type 1 diabetes by interfering with immune system signaling that causes the autoimmune attack of the insulin producing beta cells.

One way to see if the drug is working is by doing a c-peptide test. C-peptide measures how much insulin a person is naturally producing. And my c-peptide increased, meaning I’m producing more of my own insulin!!! Three months ago before I started the clinical trial my c-peptide was low at .3. My lab’s normal reference values are .8- 3.5. This time my c-peptide value was .9!!! My endo seemed surprised and said that I was “still going”. My insulin requirements have roughly stayed the same since starting the study.

So what does this mean? Is it the drug, honeymoon, or something else? There can be so many explanations and some that we don’t even know about. I just really hope the trend continues!


Unfortunately, the C-peptide test is a really lousy, non-reproducible test and sending two sample from the same draw to the same lab will give you two different results. So the answer is that the difference in your results is probably normal variation and meaningless.

I have blogged about this here:What Does that C-Peptide Result Mean.

The main thing the test shows is if you are making insulin which you are, so that’s good news. How much is really tough to measure. Are you seeing any differences in your insulin usage? If it stays constant you are not losing capacity and that’s good news.

Sorry abut the bad link: Try this.

Hey Michelle,

Too bad they didn’t get the results from the thiamine. That’s as important (if not more) than the C-peptide. Did you stimulate before the test? I’m not sure a lot of these studies are designed to accurately test the important baselines. For example, as Jenny mentioned, different labs can have different standards of deviation in readings. But the key to understanding if beta cells are working is “stimulation”. But as long as you’re getting readings – YAY!!! that’s definitely positive news :slight_smile:

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Jenny and Allie-

Thanks for the comments :slight_smile: C-peptide is more tricky than I thought! Yea, at least it’s coming back positive. Just to clarify, those results are from my endo’s office, which uses the same lab. The study is doubled blinded so they never tell me the c-peptide. And no, there was no stimulation before the test, I was just fasting.

I did get the thiamine results back and they told me it was normal! They said my thiamine value was 10 and the reference range was 8-30. I’m a bit skeptical because I didn’t actually see the results, they just told me over phone. I told the doctor and the person that took my blood several times not the enzyme test but the actual thiamine level. I still wonder if I should take a supplement anyway.

You two have really great websites!! I’ve learned a lot through them and actually because of your blog Allie, about the thiamine deficiency, I got mine checked! So, thanks!