Type 1 diabetes can occur in people with a family history of type 1 diabetes, but it can also develop in people who do not have a family history of diabetes.
The risk of developing of type 1 diabetes is increased in those who have close relatives of a person with type 1 diabetes. These include:
no family history – 0.4 percent
child of a mother with type 1 diabetes – 1 to 4 percent
child of a father with type 1 diabetes – 3 to 8 percent
child of both parents with type 1 diabetes – report as high as 30 percent
sibling (not a twin) of affected patient – 3 to 6 percent by age 20 years and 10 percent by 60 years
nonidentical twin – 8 percent
identical twin – 30 percent within 10 years of diagnosis of the first twin and 65 percent concordance by age 60 years