The immune system is comprised of different types of cells. Think of them as the military forces. In the United States, the military forces include the Army, Navy, Air Force, and Marines. Both of these are white blood cells. The B cells are the spies responsible for identifying the enemy, while the T cells are the soldiers responsible for destroying them.
B cells produce substances called antibodies.
The antibodies are like pictures identifying the enemy invaders. In Type 1 diabetes, these antibodies incorrectly identify the body's own cells as the enemy. Three particular autoantibodies are very common in people with Type 1 diabetes. They identify not only the cells of the pancreas, but also the insulin produced by the pancreas and a protein made by the pancreas as being enemies. The cells of the pancreas that are most often identified as being enemies are ones called islet cells.