Aims: To detect the incidence of childhood Type 1 diabetes mellitus (DM) (0-14 years) in Japan and to find out whether there is a seasonal pattern in the onset of disease and month of birth of children with diabetes.
Methods: Ascertained data for the period 1986-1990 could be collected in 35 out of 47 local government areas representing 69.4% of the childhood population (aged 0-14 years) of Japan.
Results: A total of 1,260 children with Type 1 DM were identified (738 girls, 522 boys). With age there was a progressive increase in incidence from 0.7 to 2.1/10(5) in boys and from 0.6 to 3.5/10(5) in girls. With the exception of 1987, when a coxsackie B3 virus epidemic was registered, no seasonal variation in the month of onset was observed, nor was a seasonal pattern of the month of birth registered in this cohort.
Conclusions: Compared to European countries, the USA and Israel, the Japanese cohort of children with diabetes presents the following differences: the incidence is much lower, there is a preponderance of girls and there is (with one exception) no seasonal pattern.