Positive Autoantibody Results 

All islet autoantibody-based risk estimates for progression
to Stage 3 T1D are based on confirmed islet autoantibody
positivity. Therefore, confirmation testing to establish
persistent islet autoimmunity is a critical part of accurate
risk communication.  

        Following positive screening results, a confirmatory visit should be scheduled to collect another blood sample and re-test islet autoantibodies using a highly-specific autoantibody assay method. Data has shown that specificity can be increased by using a different assay from the screening assay. (see Module 4).  

 

Identifying Higher-Risk Individuals for Expedited Follow-Up 

The timing of the confirmation visit should be triaged according to the risk of rapid or imminent progression to Stage 3 T1D. Ideally, those who report symptoms at screening should have had A1c testing at that time. People with a risk of rapid progression should be prioritized for a prompt return visit; this group includes those who report symptoms (polyuria, polydipsia weight loss, fatigue etc.) and/or have an elevated A1c (≥ 5.7%) or multiple positive autoantibodies at screening. The pace of progression from asymptomatic T1D to symptomatic, Stage 3 T1D is inversely related to age of onset of islet autoimmunity. Consequently, the younger the child (<5 yrs. of age) the more quickly they should be seen. Conversely, older individuals or those with a single autoantibody at screening may indicate a lower-risk status. Irrespective of risk status, confirmatory testing is still important to plan for appropriate monitoring and follow-up.

 

Testing to Confirm Positive Islet Autoantibody Results  

To confirm one or more positive islet autoantibody results, a second blood sample should be collected by venipuncture, within 3-6 months of initial screening, and tested at an accredited lab. For individuals with high risk, confirmatory testing should be performed within 0-3 months of the initial screening. All four auto antibodies (GADA, IAA, IA2A, ZnT8A) should be included in the testing.

 

Data from the Autoimmunity Screening for Kids (ASK) program shows positive confirmatory testing rates:

        • 94% for multiple autoantibody positivity at screening 

        • 93% for single autoantibody positivity by a highly-specific screening method. (see Module 4).   

        • 75% for a single positive autoantibody at screening by Radio-binding assay (RBA) methodology. 

 

Additional Testing at Confirmatory visit 

Tests/evaluation to be conducted:  

        • A1c to evaluate recent blood glucose trends over the last 3 months.
           (Note: rapid evolution of dysglycemia may be missed with this test.) 

        • Random blood glucose measures (fasting or non-fasting) for real-time measurement.  

        • Evaluation for symptoms of hyperglycemia (polyuria, polydipsia, weight loss, lethargy, etc.). 

The person/family should be educated about typical signs and symptoms of Stage 3 T1D. If there is concern regarding current symptoms, the person/family can be instructed on how to use a glucometer
to monitor blood glucose (see Module 8: Monitoring and Managing Islet Autoantibody Positive Persons).