Interpreting T1D Antibody Test Results
Egils K. Bogdanovics, MD, and Schafer Boeder, MD, discuss interpreting antibody test results for type 1 diabetes and provide recommendations for retesting for those who have a negative test or have only 1 antibody present.
Steve Edelman, MD: I think it’s important to consider that the lab may not be correct. Some of the data’s coming out that you can have false positives.
Linda A. DiMeglio, MD: Correct.
Steve Edelman, MD: Which can do a mind game on parents and kids. I know Egils has some comments regarding interpreting some of these antibodies.
Egils K. Bogdanovics, MD: Yes. Remember 2 antibodies. Stage I. It’s worth saying what antibodies we’re checking. We have antibodies to insulin itself: IA2 [insulinoma-associated protein-2], as you mentioned, GAD65 [glutamic acid decarboxylase 65-kilodalton isoform], and zinc transporter 8. Remember, if you have 2 antibodies, you have a 100% lifetime risk of developing stage III type 1 diabetes. The interpretation of different antibodies in kids, correct me if I’m wrong, it’s mostly IA2 and insulin, whereas in adults, like my 85-year-old, it was glutamic acid decarboxylase for a lot of patients. The more antibodies you have, the higher chance you will have of developing stage III disease. In the future, we’ll probably be able to categorize our type 1s based on which antibodies there are, match a phenotype to the antibodies.
Steve Edelman, MD: I think the titers are important and we don’t know 100% how to interpret these results, but it is worth repeating for sure. What happens if you have a high-risk individual, and they test negative? Schafer, do you have any suggestions when to repeat and at what age?
Schafer Boeder, MD: Dr DiMeglio can back me up on this, but my understanding is, if you are high risk, in other words, if you have first degree relatives with type 1, and you’re being tested and screened, you’re asymptomatic, but you’re being screened, if you have zero positive antibodies at that point, then you have a relatively low risk of developing stage III type 1 diabetes in your life because you’re probably not going to develop multiple antibodies from that stage on. It’s not a 0% risk, but it’s relatively low. There are some caveats that if you’re a young child and you’re at high risk and your first test is under the age of 5, then you may want to repeat that once after the age of 5. If you’re under the age of 10 and that first test is under in that time frame, you may want to repeat it after age 10 or 11. But, in general, a retest is not recommended. Does that sound right for that age group?
Linda A. DiMeglio, MD: Mm-hmm.
Schafer Boeder, MD: If you have 1 positive antibody, then that changes things and then suddenly you are at a much higher risk for eventually developing stage III type 1 diabetes. If you have 1 positive antibody, then in general, the recommendation is to repeat that test. A good time frame to do that might be 1 year later, 1 to 2 years later. I think if that’s the same recommendation in adults and kids, and that may change as we’re learning more about this and the time frame that these things occur in different age groups, but right now I think that’s a good rule of thumb to repeat it a year later.
Transcript edited for clarity
