Is type 1 diabetes hereditary?

90% of people who develop type 1 diabetes have no relative with the condition. However, genetic factors pre-dispose people to developing diabetes. Certain genes called HLA markers are associated with diabetes risk.  If a child is born with such markers, his or her risk of developing type 1 diabetes is about the same as if he or she had a sibling with diabetes, even though no other family member may have the disease.  However, not all those people who have these HLA markers develop diabetes, it is thought that some kind of trigger factor causes diabetes to develop.