Hello there FWIW - An interesting piece to the mysterious puzzle of IAA. . . For those that may not know his history,after it became clear that BK had some sort of high dose condition and after the test for Acro came back normal, BK had his first IAA test in September of 2008. The result was 84%, extreme insulin resistance. In early November of 2008 we saw a change, insulin sensitivity seemed to be returning. After that exciting first glimmer that the IAA had broken and things were turning around for BK, I wanted to have him tested again, to see if the result would be lower. His vet told me to save my money - there would be no difference. At my insistence that she humor me, she sent another blood sample to MSU. In spite of the return of insulin sensitivity the results were the same - 84%. I figured it was like someone who has been exposed to TB - once exposed they always test positive, in spite of being asymptomatic. Fast forward to the present - BK had an appointment for a blood draw recently, to check his free T4 level (he is on medication for hyperthyroid) and I requested he be re-tested for IAA at the same time, out of a burning curiosity. This type of appointment did not involve seeing his vet, the techs just draw the blood and the vet calls me with the results. The free T4 results were back the next day and the vet called to let me know the results - looking good. She said the IAA results would take about a week and asked me why I wanted him tested - she would have told me to save my money. I explained that it was a burning question for me and worth the cost just to know. To my surprise, the result was 5% (that's right, five percent. . .single digit..BK) The explanation his vet gave is that in the absence of antigen stimulation from exogenous insulin for 4+ years, no further antibodies have been produced and the ones that he had have died off . So there we have it. I'm still digesting it all.. .and more questions are forming in my mind. The world of antibodies seems so complex...and confounding.