Newly diagnosed T1 - efficacy of GAD test?

[xsarndwich]

Hi all

As a newbie, I seek your counsel once more Forum

In a nutshell - diagnosed T1 around 10 days ago - admitted to hospital on diagnosis in A&E.

Currently Insulin before meals + long acting before bed. Insulin treatment started on hospital admission via IV.

I received my GAD results yesterday of 0.2. Still need to discuss properly with doctor/consultant.

A concern though about how reliable my test is....

I read on diabetes.co.uk (http://www.diabetes.co.uk/gad-antibody-test.html) that this test should be carried out before insulin therapy begins.

Looking at the test results - the hospital carried out my GAD test when I was already 2 days into IV insulin (+ fluids/potassium/Glucose) therapy in hospital.

Anyone know if this potentially compromises my GAD result?

Thanks in advance!

C

 

[urbanracer]

As far as I know, they normally look for GAD antibodies and high blood sugar levels together. But I had my GAD test 1 yr after starting insulin and was 'strongly positive'.

EDITED:-

Info from NHS Southend University Hospital added.
Reference Range
Results shoulf be interpreted as follows

Negative result is 0-5.0 U/ml

Equivocal result is 5.1-25.0 U/ml

Positive result is >25.0 U/ml

Full text here:-
http://www.southend.nhs.uk/pathology-handbook/test-directory/test-directory-g-index/gad-antibodies/

 

[TorqPenderloin]

I did my GAD65 test after receiving insulin in the emergency room and after beginning Levemir basal injections.

I'm not aware of any proof to suggest artificial insulin can significantly affect antibody results. This study supports that: http://www.ncbi.nlm.nih.gov/pubmed/21158213

I also looked up a few other numbers for you:
-Apparently 2-4% of people with type 1 DO NOT test positive for antibodies.
-Apparently 5-10% of people test positive for antibodies, but do not have type 1 (type2 in most of those cases).

 

[Andy-Sev]

@TorqPenderloin Those statistics you got refering to those who do and don't test positive for antibodies, do you have a link to where you got them from as I had a debate with my consultant last time over this and he refused to accept that some Type 1s do not test positive for antibodies

 

[urbanracer]

@TorqPenderloin Those statistics you got refering to those who do and don't test positive for antibodies, do you have a link to where you got them from as I had a debate with my consultant last time over this and he refused to accept that some Type 1s do not test positive for antibodies

@Andy-Sev , you can find similar info within our hallowed pages, but the quoted percentages are much higher.

http://www.diabetes.co.uk/gad-antibody-test.html

 

[Daibell]

@TorqPenderloin Those statistics you got refering to those who do and don't test positive for antibodies, do you have a link to where you got them from as I had a debate with my consultant last time over this and he refused to accept that some Type 1s do not test positive for antibodies

I'm afraid your consultant is wrong. T1 can be caused by things other than GAD antibodies such as pancreatitis, viruses and so on. There are also rarer anti-bodies which aren't always included in the GAD test. Even NICE in the UK says in their latest Diabetes Guidelines that GAD tests become less reliable as the diabetes progresses, whereas c-peptide becomes more reliable. I had a GAD done 8 years after a default initial diagnosis with 'T2' and it came back as negative. In my case I suspect a virus or mild pancreatitis as a blood test taken around diagnosis time showed a high unexplained white cell count and I had mild abdominal pain. I don't think GAD tests are affected by taking insulin.

 

[tim2000s]

There's a couple of papers you can find through google scholar that show similar data to the diabetes.co.uk page.

 

[Andy-Sev]

I'm afraid your consultant is wrong.

It was one of many reasons why I walked out of that appointment deflated and why I was looking for research papers or something so that if I encountered the same consultant again I could hand them the papers. I know it's petty but it would make me feel better.