The epidemiology of insulin-dependent diabetes mellitus (IDDM) in Finland and in northern Europe.

The incidence and prevalence of IDDM are high by international standards in all Nordic countries, and Finland has the highest incidence and prevalence figures of the disease in the world. During the period 1970-1980, the mean annual incidence (per 100,000) in 0-14-yr-old children was 28.6 in Finland, 22.7 in Sweden, 17.6 in Norway, and 14.0 in Denmark. The corresponding prevalence figures were: Finland 191, Sweden 148, Iceland 141, Norway 120, and Denmark 83. Thus, on a countrywide basis the incidence increased from south to north (and from west to east). However, within some of the Nordic countries (Finland, Norway, and Sweden) there were regional variations not compatible with the above "latitude rule." As in many studies from other countries, the following characteristics were observed in the IDDM epidemiology in children and adolescents: a steady rise of incidence throughout childhood until puberty, the peak occurring earlier in girls than in boys, a male excess in young children and adolescents, a seasonal variation, and a secular trend. The possible causes of the high incidence and prevalence are briefly discussed.