Definition : When insulin attaches itself to something else. This can occur in two ways. First, when a cell needs energy, insulin can bind with the outer part of the cell. The cell then can bring glucose (sugar) inside and enables its use for energy. With the help of insulin, the cell can do its work very well and very quickly. But sometimes the body acts against itself. In this second case, the insulin binds with the proteins that are supposed to tag antigens (substances or fragments of cells) which are foreign to the body (ie, antibodies). If the insulin is an injected form and not made internally, the body may see the insulin as an outside or "foreign" substance. When the foreign insulin binds with the antibodies, it does not work as intended.