Still trying to figure what kind of diabetic am I.
Back in 2012 my C-Peptide was 765.
I was diagnosed in 2003 at the age of 17. but have always been insulin dependent.
Wondering if people with lada have notice the decreasing in C-Peptide levels over the years.
I’ve never been in dka until a year and a half ago. wondering if the C-Peptide have finally drooped. (since I know that i was a very big diabetic at times and never have gone into dka like I said… )
The normal range of C-Peptide is 0.9 to 9.1.
That equates to just over 2.3 ng/ml which is how we measure here in the US.
The figures DrJohn mentioned are widely accepted as the normal range. With that in mind, your results are on the lower-end of “Normal.”
To compare, my c-peptide when I was diagnosed 3 months ago was .7 (or about 230 depending what method of measurement you use).
It is very difficult, but even at that level I am able to keep my blood sugar in check without artificial insulin, but it requires remaining in ketosis and heavy levels of exercise.
Edit- the easy conversion rate is to multiply/divide by 331
I’m wondering also - if taking insulin and/or oral meds will effect this.
is there a difference to the test results according to how many hours of fasting before the test?
I’ve never ran into dka until a year and half ago- although there have been times that i think it was a miracle that i didn’t… unless i still had insulin.
Also - I read that one of three T1 still have insulin. but i couldn’t find the numbers as to how much they actually have… ?
A few quotes from Dr. Richard Bernstein:
“It [the C-peptide test] has to be done fasting”
“Of all my patients, I only have two who don’t make any C-peptide, and I’m one of them”
The idea behind a c-peptide test is to account for people already on artificial insulin. It would be dangerous to expect people to stop their injections altogether and test for total insulin.
My c-peptide test in 2013 showed no production at all. Dx in '96 no one knew if was definate T1. Dx in pregnancy. Always got impression was Lada. Now on insulin pump 14 months underactive thyroid too and other auto immunes. Wondering if wwas a typical T1 from beginning? Symptoms from early days of pregnancy sugar in urine fainting etc. Dx at 15 weeks. Aged just turned 26.
Personally, I think “Type 1.5/LADA” is a silly term. The reason being, is that it’s not clearly defined by the medical community, and you have no way of knowing if you’re type 1.5 at diagnosis.
The way it’s defined now is basically “Type 1 with an extended honeymoon period.” Long story short, you have no idea how long that honeymoon period is going to last until it’s over…then you become type 1 anyways.
I’m really not sure where you get your information. The medical system does not define a “normal” range for c-peptide. It is highly individualized. There are two systems for measuring c-peptide, in the US we use units of ng/ml and metric is used many other countries, either in units of pmol/ml or mmol/ml.
There is a reference range for c-peptide that is used to evaluated whether your c-peptide is meaningful. That range is typically 1-3 ng/ml but it varies from lab to lab (Quest uses 0.8-3.85 ng/ml). Each lab will define a reference range based since their test equipment and sampled populations differ.
There are actually two types of c-peptide tests, fasting and stimulated. The fasting is what is usually performed and in order to evaluate the result you need to know your blood glucose at that time. Generally if your blood sugar is high and the c-peptide is low that indicates insulin deficiency. If your blood sugar is normal but your c-peptide is high that suggests insulin resistance. The c-peptide is a crude instrument for diagnostics but is sometimes used by doctors to see if your insulin production is waning.
I’m (OCDly?) interested what my c-peptide would test out as if tested again. It’s been taken three times for me at two different labs. At each time, my BG was in the normal range, though, of course, somewhat different. The first time I tested non-fasting (around 90min after a moderate-carb meal) at 1.2 at a lab with a reference range of 0.7 - 2.1 (BG 99). Next two tests (around a year apart) were done fasting at the Mayo lab (ref range 1.1 - 4.4) and were 0.7 (BG 91) and 0.6 (BG 79) – I take those two results as statistically similar. In all three cases my doctors shrugs the tests off as interesting, but meaningless. Hm.
but what if you bg is normal + low c-Peptide ? - due to insulin shots? 
I have to be honest. If you inject insulin and take your c-peptide at a normal blood sugar then the results are probably meaningless. The exogenous (external) insulin offsets the endogenous (natural) insulin. This isn’t well recognized but I claim is likely true.
My doctor describes it as “it’s either zero, or it isn’t” in this context
Not enough, or they wouldn’t be T1.
I’m not exactly sure where your endo get’s his information. A 2010 study found that over half the 411 patients in the 50 year Joslin medalist Beta cell study had a c-peptide > 0.5 ng/ml (> 0.17 mmol/l). It is almost never actually zero. And if you inject insulin but still have natural insulin production I claim you still won’t fully shut off natural insulin production. Otherwise vast number of T1s out there would have their c-peptide tested and be zero and they aren’t.
I don’t think this is correct.
The study says that 67.4% of participants had a detectable c-peptide level (that being 0.03 nmol/l or above). However, it says that only 31 participants had c-peptide levels of 0.1 nmol/l or greater and only 14 had c-peptide levels of 0.17 nmol/l or greater. What the abstract does note is that over half of those 14 participants had an increase in c-peptide after eating a meal.
I took it to mean that the value of the lab is so limited if the patient is already taking insulin… Because like you said the exact value is essentially meaningless…
So if it’s meaningless - what is my doctor hoping to get from this test? 
“Meaningless” might be an oversimplification. I think the test has value for distinguishing early on if people are nearer the deficiency or resistance end of the spectrum. After than it can be spot checked to see if the patient is still producing a meaningful amount of native insulin… In your case, and in mine, we appear to be.
Though I do agree with Brian that the exact value becomes pretty much meaningless unless or until it becomes zero or very near zero… Which means something.
I’m no expert though.
Jen, you are correct. I misread the abstract. Yes, 67.4% had a c-peptide level > 9 ng/ml (> 0.03 nmol/L). My point is that even for long-time T1s the c-peptide isn’t just zero.
