An anti-insulin antibody (IAA) test is a quantitative or qualitative measurement of antibodies produced by the immune system that bind to the insulin molecule. These antibodies can be autoantibodies (produced against the body's own insulin, as in the early stages of type 1 diabetes) or drug-induced (produced in response to exogenous insulin used in treatment). Insulin antibodies bind to insulin and alter its pharmacokinetics and effectiveness, potentially leading to insulin resistance or allergic reactions.