C-peptide Levels After 3 Month Check Up

[nyalam]

Hello all, previously have posted on the Type 1.5/LADA forum as this was my initial diagnosis at end of May there. I had an HBa1c of 10.7% / 93 at that time and had an according C-Peptide result of 1.63 ng/mL (or 0.539 mol/L). I managed to gain a level of control over my diabetes quickly through mainly diet and increasing exercise, but was also on 6U per day of Lantus and 2 metformin again daily. After a month I had the antibodies tests done for GAD and the other two main ones (islet cells and anti-insulin or whatever) and they all 3 came back as negative. Im based in Russia most of the time so was able to get all this testing carried out easily albeit at own expense.

Came back to UK and visited NHS who carried out relevant blood and urine tests which showed my HBa1C was now at 7% / 53 (at start of July) and nothing came up to indicate any sort of diabetes related kidney, liver or heart complications. Cholesterol etc fine and lower than normal - they surmised that I most likely wasn't a type 1 / 1.5 but most likely a type 2 of normal weight but with genetic links (grandmother, two uncles developed it albeit in 60s and 70s and I'm 34) Also went private to endocrinologist who looked at all my data and said I would be very unlucky to be type 1 / 1.5 given the negative antibodies and fact I hadn't experienced rapid and unexplained weight loss etc.

Now had my 3 months check up back in Russia - HBa1C of 5.2 / 33 which I am delighted with but with me now not having as much sugar polluting my system also saw a reduction in my C-Peptide to 1.087 ng/mL (0.36nmol/L). I am hopeful this is a natural reaction to my body needing less insulin, and can see that the normal range of C-Peptide is between 0.5-2 ng/mL), thus would like to enquire if anyone can shed light / experience on C-Peptide levels and how 'normal' should normal be?

Both C-Peptide tests were done fasting and apologies if ng/mL or mol/L aren't the units used for measurement in UK.

Cheers

John

 

[Lally123]

Hello all, previously have posted on the Type 1.5/LADA forum as this was my initial diagnosis at end of May there. I had an HBa1c of 10.7% / 93 at that time and had an according C-Peptide result of 1.63 ng/mL (or 0.539 mol/L). I managed to gain a level of control over my diabetes quickly through mainly diet and increasing exercise, but was also on 6U per day of Lantus and 2 metformin again daily. After a month I had the antibodies tests done for GAD and the other two main ones (islet cells and anti-insulin or whatever) and they all 3 came back as negative. Im based in Russia most of the time so was able to get all this testing carried out easily albeit at own expense.

Came back to UK and visited NHS who carried out relevant blood and urine tests which showed my HBa1C was now at 7% / 53 (at start of July) and nothing came up to indicate any sort of diabetes related kidney, liver or heart complications. Cholesterol etc fine and lower than normal - they surmised that I most likely wasn't a type 1 / 1.5 but most likely a type 2 of normal weight but with genetic links (grandmother, two uncles developed it albeit in 60s and 70s and I'm 34) Also went private to endocrinologist who looked at all my data and said I would be very unlucky to be type 1 / 1.5 given the negative antibodies and fact I hadn't experienced rapid and unexplained weight loss etc.

Now had my 3 months check up back in Russia - HBa1C of 5.2 / 33 which I am delighted with but with me now not having as much sugar polluting my system also saw a reduction in my C-Peptide to 1.087 ng/mL (0.36nmol/L). I am hopeful this is a natural reaction to my body needing less insulin, and can see that the normal range of C-Peptide is between 0.5-2 ng/mL), thus would like to enquire if anyone can shed light / experience on C-Peptide levels and how 'normal' should normal be?

Both C-Peptide tests were done fasting and apologies if ng/mL or mol/L aren't the units used for measurement in UK.

Cheers

John

Hi John, I am also LADA diagnosed a few months ago and switched diagnosis from T2. I had negative GAD and a low C peptide but I'm pretty certain that when I had the C peptide test done I had to eat first and was told it would be unreliable if done fasted? Not sure why you were told to fast, or whether it really makes any difference. Hopefully someone who knows more will be along to advise you soon!

 

[ringi]

The "standard expected range" for C peptide is based on people eating 150g of carbs a day, hence it is normal for C peptide to be a lower for people on a low diet. Personally I think you should pat yourself on the back, keep doing what you are doing, and ignore the c peptide result. (c peptide is useful if a1c, or fasting BG is high)

 

[Canvaspic]

A few thoughts.

If you are still taking insulin, and are achieving very normal BG. Then your own pancreas will produce less insulin ( and therfore less c-peptide) . Ie in your situation you cant separate the effect of injecting, vs own insulin production. If you were running higher BG e.g average 8mmol/L then your pancreas would be giving maximum effort, and therefore CP would be a indication of insulin production.

Fasting c-peptide only has context with fasting BG. A low CP and high BG, would be indicative of low beta cell function. I have seen a ratio of 11 used as a cutoff ( when using BG in mmol/L and CP in nmol/L ). The University of Oxford has a HOMA insulin resistance calculator ( https://www.dtu.ox.ac.uk/homacalculator/ ) , which also covers beta cell function. It accepts fasting insulin or c-peptide and fasting BG.

Researchers favour stimulatied c-peptide over fasting CP as it gives more reliable results. In general its an achievement for any patient to get any CP test done. Fasting is better than no test.

My last CP test had a range of .34 to 1.8 nmol/L, I have seen “normal” of (.5 to .88), (.2 to 1.3) and lots inbetween. What I am trying to understand for myself is what is the lower number where insulin would start to make sense.

 

[Gina G]

Interesting ...my son had 3 tests done anti GAD, 1A2 and a ZnT8 (zinc transporter 8 test)
His c peptide normal range, GAD and 1A2 test negative...ZnT8 positive
Doctors letter said having the ZnT8 positive, is consistant with type 1

He is still on no insulin following good diet, bs all in normal range, had to come off it after 6days as his bs too low.

My son is waiting for an appointment with specialist as he feels he is in no-mans land as his last hospital appointment were very unsure of his diagnosis
Very frustrating