C Peptide Experiences/opinions

pawprint91

pawprint91

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Type 1
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Hi all,

In another thread I posted about a new consultant querying about whether I am type 1 or LADA due to my TIR and has sent me to have a c peptide blood test.


I have had no other instructions other than a blood form and regular blood appointment. In my original thread, it was said that c peptide tests often require you to eat a carb heavy meal beforehand to test your insulin production and push your BG into the teens. I have a colleague who has just had a c peptide test and she didn’t have to do this, so I’m just wondering - what are other people’s experiences?
 
I had to fast. That now seems rather peculiar.
 
I think part of the problem with C-peptide tests is that the people requesting them either don't know what the test involves or don't give the patient any info about preparing for it. Most other blood tests don't need any special prep, so they either forget or don't realise that this is the case.

I believe the test can be either a fasted test or a carb loaded test and they measure the BG of the blood sample along with the C peptide test and I believe there are two sets of parameters one each for fasted or loaded.
I had to have breakfast without insulin a couple of hours before mine. It was a senior consultant who requested it. The sample also needs to be frozen within 20 mins of being drawn I believe and then sent off to the lab frozen. This process usually involves dry ice for quick freezing so most GP practices are not set up to take the sample and I had to go to the main hospital (I saw the consultant at the local hospital but they didn't have the necessary facilities either) to have the blood drawn and processed for shipping to the lab.
 
T1 and LADA are essentially the same thing and you should be treated as T1 in my opinion - they are both an auto-immune condition which stops your pancreas from producing insulin (i.e. T1) so I don't understand why the powers that be would muddy the waters - I was 47 when diagnosed and LADA was never mentioned once (I only found out about the term on this forum)
 
Looking at some of the literature there is an indication that non fasting is a better predictor as c-peptide is produced in equimolar amounts to insulin so if fasting there is little demand for insulin but there are different parameters for results depending on whether the sample is fasting, non fasting or random.
The test is used for several different purposes and that may determine the type of sample it needs to be.
It would be better to check with whoever requested the test if you can.
 
Mine’s at lunchtime, but I won’t have eaten for 5+ hours before it.

rebrascora said:
I had to have breakfast without insulin a couple of hours before mine. It was a senior consultant who requested it. The sample also needs to be frozen within 20 mins of being drawn I believe and then sent off to the lab frozen. This process usually involves dry ice for quick freezing so most GP practices are not set up to take the sample and I had to go to the main hospital (I saw the consultant at the local hospital but they didn't have the necessary facilities either) to have the blood drawn and processed for shipping to the lab.
Click to expand...
This new consultant told me it used to have to be done in an hour but now they can do it in 8 hours, so I am able to go to the local hospital rather than the main one! (But realistically they are not that far apart - within an hour of one another!)
 
pawprint91 said:
Mine’s at lunchtime, but I won’t have eaten for 5+ hours before it.


This new consultant told me it used to have to be done in an hour but now they can do it in 8 hours, so I am able to go to the local hospital rather than the main one! (But realistically they are not that far apart - within an hour of one another!)
Click to expand...
That probably counts as a random sample as fasting would be 8-12 hours and non fasting would be eating just before or being given glucose as part of the test procedure.
 
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