Upcoming change to diabetes antibodies 

There are upcoming changes to how diabetes antibodies will be run within the Awanui laboratories.  As some will be aware, islet cell antibodies are currently unavailable in New Zealand due to issues with the immunofluorescence slides.  It is increasingly recognised that islet cell antibodies have a limited clinical utility in the diagnosis of type 1 diabetes and in isolation have limited utility for assessment of risk of type 1 diabetes. 

GAD and IA2 antibodies remain available to, or on the advice of, Endocrinologists/Diabetologists.  E-ordering of diabetes antibodies will be available with prompts for the advising endocrinologist and clinical details, we would recommend including these if using manual forms as well to reduce the risk of delays in testing. We are changing to running both antibodies up front from 10 July 2024 in our Wellington Laboratory as a diabetes antibody panel as there is evidence that this reduces false negative rates and can also improve specificity. 

A newer test, anti-zinc transporter 8 (ZnT8), is also now available in New Zealand as per local policies and is usually requested where GAD and IA2 are both negative and there is a specific need to clarify Type 1 versus Type 2 diabetes.  This will generally be requested by an Endocrinologist.  The risk of progression to type 1 diabetes or likelihood of a patient having type 1 diabetes is higher where there are more positive antibodies.   It is important to note that a weak positive result is of uncertain clinical significance and should not be taken as diagnostic of type 1 diabetes.  Antibody testing can be a part of assessment for type 1 diabetes but must be interpreted carefully alongside the clinical situation and other tests such as C-peptide where appropriate.  Diabetes antibodies are most accurate when tested at diagnosis of diabetes and sensitivity may be lost over time.

Anti-GAD antibody for neurology purposes remains available but must be requested by or on the advice of a neurologist and the request must include the Neuronal Antibody request form found here

Dr Arthur Price 
SMO Immunopathologist 
Awanui Labs – Wellington 
Wellington Hospital

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