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C-peptide, fasting insulin and type of diabetes

finsit

Well-Known Member
I have a quick question about someone in the family who was diagnosed with diabetes. Here is the data and i am trying to make sense of it.

Male, 28 years age
A1c in Sept 2021: 13.3%

After following low-carb and no meds, his stats are:
a1c in January 2022: 6.6%
fasting insulin: 4.5 (same time fasting BG was 120 mg)
post prandial c-peptide: 5.5 ng/ml

It seems he doesn't have insulin resistance. it also seems he is producing good amount of insulin from postprandial c-peptide. So my question is, is he still a type-1 or its type-2 and should he be using insulin or treatment instead? What's your opinion?

There is a family history of diabetes T2, he has no other illnesses and had been operated in 2015 for hernia.

Thanks.
 

Hi @finsit

So I'm not understanding part of your question and I seek clarification.

Your friend was diagnosed as T1 with an A1c >13% and I would assume given insulin to inject at least twice a day - maybe more if on a basal/bolus regime???

Then a second A1c test recently has come back at 6.6% which being above 6.5% which (here in the UK) is still technically cause to diagnose diabetes . Is this not evidence that the injected insulin is doing its job?

For T1's there is something called the Honeymoon Period where a person's pancreas can start producing a little insulin again once injected insulin takes the pressure off. This period may last weeks or months and possibly even a year or more depending on the individual. Usually, the pancreas will stop producing insulin altogether and your friend would then have to rely on injected insulin to control glucose levels.

Has your friend also had a GAD antibody test? What was the result?

It is often very difficult to distinguish between T1 and T2 and can come down to arbitary observations about body mass and lifestyle. Adult T1's usually present with sudden uncontrollable weight loss, frequent urination (Polyuria) but not much coming out and blurred vision. Did your friend experience any of these symtoms?

Regards
Urb'
 

Thanks Urb, I am not sure if i mentioned or not, but he is not on any medications or insulin. The decrease in a1c is purely with the diet. I understand honeymoon period and this may be the case. No he didn't do any antibodies tested. So is it only GAD or something else he needs to test as well ? My question remains that in the absence of insulin resistance and perfectly fine insulin production postprandial, why his fasting is still in 120's and do you or anyone else thinks with diet he would be able to control it for long? I assume Metformin would be of some benefit here.
 
Is your family member overweight?

I am a little confused as to how he could be T1 if he's managed for a year without insulin, though I appreciate that LADA can progress slowly, particularly if controlled by low carb.

What does his doctor say about this? Given his age he might be able to ask for a referral to an endocrinologist. There are other types of diabetes (eg MODY, which I really don't understand).

But really these are questions that he should be asking his medical team. We aren't allowed to diagnose on the forums.
 

We obviously cannot diagnose over the internet but if your friend is managing without injected insulin of any sort then he's probably not T1. A T1 with a very low carb diet may acheive acceptable glucose results for a while if the pancreas is still producing some insulin but this is not easy to do and the results may be shortlived.

T2 is easier to control (in the longer the term) with a diet that is low in carbohydrate.

The GAD antibody test is not foolproof but my own result read something like "strongly positive" and this was taken as confirmation of the T1 diagnosis. Ideally this would be done in conjunction with the C-Peptide test which you already have.

I'd reccomend that your friend goes back to the doctor for further investigation in the hope of acheiving a correct diagnosis.
 
Thank you both for your reply. He is not overweight at all and no central obesity either. He is not in UK and lives in a deprived area, so i am helping him out with few tests so then he can go out to a bigger city and do a proper consultation. Yes are not diagnosing but i am just trying to solve this puzzle of T1 vs T2. I don't know much what comes in the middle, like MODY etc
 

Hi,

It's not always clear what comes in the middle.
But what comes next should be a consultation from an HCP.

Best wishes to your friend with official confirmation of diagnosis.
 
A normal c-peptide result should be between 0.5 to 2.0 nanograms per milliliter (ng/mL). An elevated c-peptide of 5.5ng/ml would support insulin resistance and type 2 diabetes at this stage. This is something for him to discuss with his consultant.
 
His fasting glucose is still high but the fasting insulin doesn’t seem especially high in order to counter it, as one might expect. Depends on many factors. His glucose may have been coming down at the time of the measurement, which would probably mean insulin levels falling off. My first thought is type 2 pathology which has been massively improved with a low carb intervention but he has a pancreas struggling to keep up with the glucose. This isn’t uncommon and can often be improved in the passage of time. Nothing in that data makes me think type 1, but of course the honeymoon phase can’t be ruled out. I would say keep calm and carry on with the low carb but stay vigilant. Forever.

PS. HOMA-IR calcs can be a bit noisy. It’s easy to say no insulin resistance if the insulin is not high but the glucose is only marginally high. In reality the pancreas might be going hell for leather trying to keep up and be maxed out. I call type 2 that is borderline under control but needs more work. Of course that is an opinion and not a diagnosis.
 
Last edited by a moderator:
@finsit , many of the questions you ask cannot be answered on the forum, it would break forum rules.
finsit said:
He is not in UK and lives in a deprived area, so i am helping him out with few tests so then he can go out to a bigger city and do a proper consultation.
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How did he get a C-peptide and fasting insulin test if he lives in a deprived area? Those are not tests that are easy to get even in the UK or the Netherlands.
finsit said:
Yes are not diagnosing but i am just trying to solve this puzzle of T1 vs T2.
Click to expand...
Solving this puzzle is diagnosing.
You won't be able to draw a conlusion from the results, as they are inconclusive.
finsit said:
so i am helping him out with few tests
Click to expand...
Be careful, you might do more harm than good trying to interpret health tests without the needed basic knowledge. Being a member on a forum and reading around the internet doesn't substitute a study to become an endocrinologist.
 
Hi Antje, the person lives in Pakistan. Now getting tests are much easier even in remote areas in Pakistan, finding an endocrinologist is not. Definitely, that was my advise to him as well. He is curious to know the difference and he has been reading, so I thought I will see what forum people would say. Definitely, no diagnosis or treatment.
 
Getting antibodies tests would probably be worthwhile, if it is left too long the results can be inconclusive. There are a number of antibodies which are tested for associated with diabetes not just GAD. The antibodies test could confirm an autoimmune component, it can not rule out an autoimmune component because there may be antibodies which are not tested for (because unknown or no practical test available). I think the ZnT8 antibodies were the last added to the current list in around 2016.
I also think it is probably worth him keeping a record of fasting blood glucose to see if there is an upward trend despite being on low carb.
 
It’s so not straight forward, I was not on insulin for several years, controlled with diminishing effect by LCHF yet was rediagnosed, I would say live on low carb and keep numbers as low as possible for as long as possible if no access to appropriate doctor, I can’t see any harm in acting as a T2 until they can’t anymore. For me, the treatment for both types is the same so makes little difference to me which type I am, the main differences is, doctors, nurses and dieticians are nicer to me now, honestly. *shrug*
 
@finsit - I totally understand your desire to help a family member having challenges in life, however, one of the potential ptfalls of this is giving guidance, or making observations taken by the other party as a diagnosis (even if warned not to), then acting upon it - only to find it was wrong. That could end up in a very scary and serious situation.

I would also urge you to remember that T2 is not about becoming fat, but the individual becoming fatter than their own body can cope with. Additionally, different ethnic groups and races can exhibit different characteristics when it comes to diabetes. For example, Asian populations are monitored for BMI healthy ranges differently - usually leaving the Healthy range over 23.

So, my strong advice to you would be to advise your relative to seek formal medical advice. As he seems to be doing well, having significantly reduced his A1c, he should likely continue with whatever he is doing.

Has the young person had their eyes checked in recent weeks? That A1c reduction from 13.3% to 6.6% is very dramatic. It is an unfortunate, but harsh fact that rapid blood sugar reduction can cause eye damage in some individuals.

I hope the young person finds good health and keeps it.
 
AndBreathe said:
Has the young person had their eyes checked in recent weeks? That A1c reduction from 13.3% to 6.6% is very dramatic. It is an unfortunate, but harsh fact that rapid blood sugar reduction can cause eye damage in some individuals.
Click to expand...

This cannot be overstated. Bringing prolonged and very wayward diabetes rapidly under control can give your eyes a real pasting.
 
Jim Lahey said:
This cannot be overstated. Bringing prolonged and very wayward diabetes rapidly under control can give your eyes a real pasting.
Click to expand...

It screwed me over..
I believe both you & I have experience on the treatment with that "one." (I'll say no more..)
& yes I was as "rocking" a 6.5 at the time.? From some abysmal figures.
 
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