Why the Immune System Attacks
Reviewed by CDE Mehandi Sharma · Updated
Your immune system exists to attack things that do not belong in your body — bacteria, viruses, infected cells. In an autoimmune condition, it makes a mistake and attacks something that does belong.
In Type 1 diabetes, the target is the beta cells of the pancreas, the cells that make insulin. The immune system treats them as foreign and destroys them. This happens gradually, often over months or years, and symptoms only appear once most of those cells are already gone.
That destruction leaves traces called autoantibodies, which can be measured in blood. Their presence is what confirms the condition is autoimmune — and it is the test that separates Type 1 from other kinds of diabetes when the picture is unclear.
What triggers it is not fully known. Both genetic and environmental factors appear to be involved. Certain gene variants make a person more susceptible, but carrying them does not mean the condition will develop, and something in the environment seems to have to happen as well.
That is an unsatisfying answer, and it is the honest one. Research is active and ongoing.
What is clear is what does not cause it. Nothing about how much sugar someone ate, how much they weighed, or how they were brought up sets this in motion.