Increasing incidence of diabetes mellitus in Norwegian children 0-14 years of age 1973-1982.

A retrospective technique was used to register all newly diagnosed cases of diabetes mellitus in Norwegian children 0-14 years of age during the ten-year period 1973-1982. A total of 1,914 newly diagnosed cases were detected, from an average population of 932,037 children. The degree of ascertainment was near to 99%. The male incidence exceeded the female incidence by 12% (p less than 0.02). The mean yearly incidence for the ten-year period was 20.5 per 100,000. Comparing the two five-year periods 1973-1977 and 1978-1982, the mean yearly incidence increased from 18.5 to 22.7 per 100,000 (p less than 0.0001). There was a marked geographic variation with the highest incidence in the south-east and lower incidence in the northern part of the country. However, in the northern part of the country, there was a remarkable increase of the annual incidence from the first to the second five-year period (12.9 vs 19.3 per 100,000). The highest numbers of new cases were detected in the months of January and October, and the lowest numbers in May and July. The seasonal pattern was significantly different from a uniform distribution of new cases throughout the year (p less than 0.001). The age-specific incidence increased towards a peak at 12 years for both sexes. In conclusion, Norway has a high and apparently increasing incidence of childhood diabetes. The geographic variation and secular trend present challenging clues for a search of etio-pathogenic factors.