The frequency of diabetes in children of type 1 diabetic parents.

There is little information in the literature about the actual diabetes risk of children of Type 1 diabetic parents. In a follow-up study of 48 children born from 35 Type 1 diabetic parents between 1955 and 1989, we have recorded all data relating to the incidence of Type 1 diabetes and of appearance of signs of subclinical diabetes by June, 1992. Information about the state of health was obtained during repeated stays of the patients in our hospital or by interviewing them by letter. In 21 children aged between 4 and 29 years who had not developed diabetes, we were able to investigate oral glucose tolerance, first phase insulin secretion, islet cell antibodies and insulin autoantibodies. HLA-typing was performed in 69 of the 118 study subjects (children and their parents). Type 1 diabetes developed in 19 out of 48 offspring of Type 1 diabetic parents. Frequency is also 25% in those 24 offspring born before 1972. The children developed the disease significantly earlier than the parents (8.2 +/- 6.0 versus 15.9 +/- 8.3, p < 0.01). Diabetes became manifest in 4 single children, in 2 HLA-identical pairs of siblings, and in 4 children with non-diabetic siblings. In 5 out of 21 non-diabetic offspring investigated we found impaired glucose tolerance, diminished first-phase insulin secretion, and/or Islet Cell Antibodies between 5 and 80 JDF units. The frequency of diabetes in the offsprings of Type 1 diabetic parents was lower than expected, but in addition 24% of the non-diabetic children displayed signs of subclinical diabetes.