Nationwide, Prospective Registration of Type 1 Diabetes in Children Aged <15 Years in Norway 1989–1998

Abstract

OBJECTIVE—An increasing incidence rate of childhood-onset type 1 diabetes has been described in several countries, particularly among the youngest children, and the Nordic countries have consistently been shown to have the highest incidence rates. An increasing incidence had previously been reported in Norway for 1973–1982, together with regional variation within the country. The aim of this study was to test whether there has been an increasing incidence of type 1 diabetes and a continued regional variation among children aged &lt;15 years in Norway during 1989–1998. RESEARCH DESIGN AND METHODS—As a part of the activities of the National Childhood Diabetes Registry of Norway and the EURODIAB study, a 10-year prospective, nationwide case registration of type 1 diabetes was done among children aged &lt;15 years. RESULTS—A total of 1,867 new case subjects (1,009 boys and 858 girls) were identified. The total incidence rate was 22.4 per 100,000 person-years (95% CI 21.5–23.5). The incidence was 13.1, 26.3, and 28.8 per 100,000 in the age-groups 0–4.9, 5–9.9, and 10–14.9 years, respectively. No increase or decrease over time was detected in any of the age-groups during the 10-year period. We found significant variation between the 19 counties, which only partly reflected the pattern previously described for 1973–1982. CONCLUSIONS—We found a significant regional variation within Norway. After a previous period of increase, the incidence has been stable in all age-groups &lt;15 years during 1989–1998.