Our data provide additional evidence that childhood-onset Type I diabetes carries an increased mortality risk when compared with the mortality risk of the non-diabetic population.

Israel is a country with low, intermediate, and high incidence of childhood IDDM. The interethnic differences in incidence are probably due to genetic factors. However, the significant increase in incidence since 1985 in the Jewish population is ascribed to thus far unidentified environmental factors. It is hypothesized that the marked increase in IDDM is due to environmental factors linked to changes in affluence and lifestyle. These may also explain the difference in incidence between the Jewish and Arab populations, the latter living more in rural areas and leading a more traditional lifestyle.

The aim of this study was to find out whether there is a seasonal pattern in the month of birth of children with IDDM in Israel and whether this pattern, if present, differs from that of total live births. One thousand and ninety-five out of 1,188 children and adolescents (0-17 years) who developed IDDM in Israel between 1980-1993 and whose month of birth was known were included in the study. Separate analysis was made for Jews (n = 987) who have a high incidence (10-18/105) and Arabs (n = 108) with a low incidence (2.9/105) of IDDM. The pattern of total live birth distribution in Israel over a 20-year period served as control. A significantly different seasonal pattern was found in the two IDDM populations. Whereas the Jews had the lowest number of births in winter (January-March) and the highest in spring (April-June), the Arabs presented an inverse pattern in the first months of the year. The distribution of births of the children who developed IDDM was different from that observed in total live births in the Jewish population. The findings in the Jewish population in Israel (a high incidence group) support the hypothesis that IDDM is triggered in some children by viral infections transmitted by the mother during pregnancy or in the early postnatal period. In the Arab population (a low incidence group) a protective (immune and/or genetic) mechanism may exist.