I have been told that type 1 diabetes is hereditary. I was diagnosed in 1966 at the age of seven. No one else in my family was ever diagnosed. So, if it is hereditary, why am I the only one is my genealogical history that has ever been diagnosed?

The inheritance pattern for type 1 diabetes is different than that of type 2 diabetes. For offspring of parents with type 2 diabetes, there is roughly a 50% chance of inheriting diabetes. For those with type 1 diabetes, it is much less, at around 10%. This means that many people develop type 1 diabetes without other recent members of their family having had the disease. We believe that type 1 diabetes has a complicated inheritance pattern where you inherit a predisposed risk for the disease, but also require some environmental hit, such as an infection or another exposure, to get the disease. It is also interesting that men with type 1 diabetes have a slightly higher risk of offspring developing type 1 diabetes, compared to women. The risk is something like 10 to 15% for men, but only 5 to 10% for women.

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