A 60-fold international gradient in IDDM incidence has been reported and epidemic periods have been identified. Mannerheimintie 166 FIN 00300 Helsinki, Finland Tel. 1211 Geneva 27 Switzerland Tel.
Data is now available from more than half of the centers.
The highest incidence in the world is in Northern Euroe, but within the continent there are striking exceptions as in Iceland the incidence is only half of that in Norway and Sweden and one-third of that in Finland. By contrast, in Sardinia, in Southern Europe, the incidence is almost as high as in Finland, three times higher than the overall incidence in Europe. The lowest incidence is seen in Japan, Korea and Mexico. Genetic Substudies Case-Control Molecular epidemiology studies are being carried out to assess the contribution of HLA alleles to the incidence of IDDM within and between populations. Data from case-control studies are available from 18 populations, including high, medium and low risk areas and various racial groups.