Insulin autoantibodies as determined by competitive radiobinding assay are positively correlated with impaired beta-cell function — The Ulm-Frankfurt population study

Out of a random population of 4208 non-diabetic pupils without a
family history of Type I diabetes 44 (1.05%) individuals had islet
cell antibody (ICA) levels greater or equal to 5 Juvenile Diabetes
Foundation (JDF) units. 39 of these ICA-positives could be
repeatedly tested for circulating insulin autoantibodies (CIAA)
using a competitive radiobinding assay. The results were compared
with the insulin responses in the intravenous glucose tolerance
tests (IVGTT) and with HLA types. Six pupils were positive for
CIAA. All of them had complement-fixing ICA, and 5 of them were
HLA-DR4 positive. Three of the 6 showed a first-phase insulin
response below the first percentile of normal controls. Our data
indicate that in population-based studies CIAA can be considered as
a high risk marker for impaired beta-cell function in non-diabetic
ICA-positive individuals.