Prospective Study of Insulin-dependent Diabetes Mellitus

Laboratory study of 109 insulin-dependent diabetics younger than 17 yr of age and resident in greater Montreal at the time of onset of symptoms is reported. The cases were diagnosed during a 2-yr period (1976- 1978). Sibling controls were obtained for 72 of the cases studied. Viral titers to Coxsackie B, rubella, and mumps viruses for the 72 patient-sibling pairs showed no difference in geometric mean titers or in change of titer between samples taken at the time of diagnosis and those taken 28 days later. The incidence of positive islet cell antibody in the IDDM cases was 68.0% at the time of diagnosis compared with 56.9% 4 wk later. The comparative figures for sibling controls were 4.2% and 1.4%, respectively. The frequency of HLA B8, B15, B18, and B7 antigens were compared both with the sibling controls and a normal control population. Pairings of high risk HLA antigens were found more frequently in cases than controls. There was no difference in geometric mean viral titers in cases with high risk haplotypes compared with those cases in which such haplotypes were absent.