The Risk to Brothers and Sisters
Reviewed by CDE Mehandi Sharma · Updated
After a diagnosis, the question comes quickly: could this happen to our other children? Or to a future child?
The honest answer has two halves. Having a parent or sibling with Type 1 diabetes does raise the risk compared with the general population. And most people who develop Type 1 have no family history at all, which is why the diagnosis so often arrives with no warning.
So the increase is real but it is not a prediction. The great majority of siblings of a child with Type 1 will not develop it.
What is measurable is autoantibodies. The same antibodies used to confirm a diagnosis can be detected in some people before any symptoms appear, and their presence indicates the process has started. Testing a sibling is possible and is sometimes offered through research programmes.
Whether to test is a genuine decision rather than an obvious yes. A negative result is reassuring but not permanent. A positive result tells you something is under way without telling you when, and that knowledge is heavy to carry.
What is unambiguously useful is knowing the warning signs for the whole family. A sibling who starts drinking and passing urine constantly gets tested that week rather than that month, and that alone prevents most cases of a second child arriving in DKA.