If you test positive for all three antibodies, does that mean you are automatically a type 1 diabetic? If my daughter had negative antibodies at diagnosis, could putting her on exogenous insulin cause the body to make insulin antibodies therefore making a later antibody test be positive?

Antibody testing just says that there is some autoimmune response going on vis-a-vis the pancreas. So, that produces “risk” that this will change/progress to beta cell damage and thus type 1 diabetes with need for insulin injections. It is very helpful to categorize different types of diabetes and very helpful for some patients to know the risks of medical intervention trials to help change or prevent diabetes, i.e., brothers and sisters, other relatives, kids. Research has demonstrated the more positive the antibodies and the more different antibody tests that are abnormal (i.e., positive), the higher the risks of developing diabetes (or of having type 1 rather than type 2). However, about 20 to 30% don’t ever have antibodies so one can still have type 1 diabetes and be antibody negative. You are also correct that when insulin is started, antibody levels change but only for the actual insulin antibody, not for the other three. Antibody levels tend to be highest at diagnosis or for several years before actual diagnosis and tend to decrease or go away over time so more important early in the course of diabetes development rather than later.

SB