[Markers for risk of IDDM in children of Danish patients with IDDM. A population-based, historical prospective study]

To assess the offspring IDDM recurrence risk in a Danish population-based study and to investigate parental and offspring related biological variables that might influence this risk, we identified 2726 IDDM probands and their 2826 offspring from a background population of 1.725 million people (33% of the Danish population). Proband current age was 20-60 years and age at IDDM onset was 30 years or less. Offspring data were obtained by a questionnaire. The cumulative IDDM risk up to age 30 years was found significantly decreased in maternal offspring compared to paternal offspring (2.3 +/- 0.6% and 5.7 +/- 0.9%, RR = 2.40, 95% CI 1.30-4.47; Mantel Cox: p = 0.004) only if parents were diagnosed with IDDM before offspring birth. However, due to a low number of diabetic offspring of probands diagnosed with IDDM after offspring birth, this observation need to be confirmed in a larger population. Using the Cox proportional hazards model we found that among several biological variables tested separately on offspring of male and female probands, all diagnosed with IDDM before pregnancy, paternal age at IDDM onset was the only statistically significant predictor of IDDM risk in offspring. Our findings may be important for counselling families in which one parent has IDDM.