GAD antibody testing

Freethinker

Member
Messages
10
Type of diabetes
Type 2
Treatment type
Insulin
As I was not overweight when diagnosed and went quickly onto insulin, it has been suggested that I might have LADA, but the NHS will not test me now. I have found that I can get the test for GAD antibodies done privately, but does anyone know if it is too late - i.e. now that I am on insilin will it affect the test results?
 

borderter

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638
Type of diabetes
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Diabetes! Celebrities and curry
Hope you get some answers as am interested being in a similar situation :)
 

catapillar

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3,390
Type of diabetes
Type 1
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Insulin
I don't think insulin impacts on the accuracy of the antibody tests - either you have antibodies or not. Taking insulin shouldn't affect that. However, it has been suggested that what might have an impact on an antibody test is how long since diagnosis you are having the test run - so if it's a long time past diagnosis it is suggested that a negative antibody test won't necessarily mean that you never had antibodies.
 
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chalup

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1,745
Type of diabetes
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A c-peptide test might shed some light on whether the need for insulin is because of insulin resistance (type 2) or insulin insufficiency (type 1 or type 2 with advanced disease) if you don't already know.
 

Freethinker

Member
Messages
10
Type of diabetes
Type 2
Treatment type
Insulin
Mmm - 16 years since diagnosis so maybe too late for the test, thanks catapillar will try to look into that. And chalice, do you know if the c-peptide test would be affected by time since diagnosis?
 

chalup

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Type of diabetes
Type 2
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C-peptide is formed when insulin is produced so the c-peptide level tells them the amount of insulin you are making on your own at the time of the test, usually fasting. Injected insulin also won't interfere. Time since diagnoses does not enter into it the way it might with GAD testing.
 

borderter

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Messages
638
Type of diabetes
Type 2
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Diabetes! Celebrities and curry
Can cpep be done privately do you know
 

Freethinker

Member
Messages
10
Type of diabetes
Type 2
Treatment type
Insulin
Yes, both tests can be done by medi-labs.com - the price is £99 for GAD and a bit more for c-peptide
 

catapillar

Well-Known Member
Messages
3,390
Type of diabetes
Type 1
Treatment type
Insulin
I was ver strongly GAD positive 4 years post diagnosis and it is possible to be GAD positive long past that.

Maybe the story of your diagnosis will give more clues as to possible type
  • How old were you when diagnosed?
  • What was your BMI
  • Had you experienced sudden, untried for, dramatic weight loss prior to diagnosis?
  • What were your blood sugar levels like on diagnosis? Were they in the 30s?
  • Did you have DKA?

How is your diabetes treated? If you are already on insulin, is there a practical benefit to having a type determined? Or is it to satisfy curiosity/peace of mind?
 

Freethinker

Member
Messages
10
Type of diabetes
Type 2
Treatment type
Insulin
Hi Catapillar - yes, it is just curiosity - diagnosed age 38, BMI in normal range, no sudden weight loss, but blood sugar levels were in the 30s -(I remember one nurse saying that people with those levels normally came in horizontally!) - at the time I also had thyroid problems and have gone on to develop rheumatiod arthritis, which makes me think more and more it may have been LADA
 

Daibell

Master
Messages
12,642
Type of diabetes
LADA
Treatment type
Insulin
Hi. Yes, LADA is quite possible. The GAD test is not affected by insulin but as Catapillar says, the result is less reliable as the year pass after diagnosis. The c-peptide does indicate whether you are lacking in insulin (T1) or have too much (T2). It is also unaffected by insulin. I had both tests done privately by Medi-Checks and cost around £350 total about 5 years ago. My GAD was negative around 8 years after diagnosis but my c-peptide was at the bottom of the range.