Ethnic Differences in the Incidence of Childhood IDDM in Israel (1965–1993): Marked increase since 1985, especially in Yemenite Jews

Abstract

OBJECTIVE To establish the changes in the incidence of childhood IDDM during the years 1965–1993 in the different ethnic groups in Israel. RESEARCH DESIGN AND METHODS A whole-country register of childhood IDDM (0–17 years) was started in Israel in 1965. Onset of IDDM was considered to be the date of first insulin injection. The data were collected from all outpatient clinics and hospitals. Ascertainment is estimated to be over 95%. RESULTS A total of 1,868 patients were registered for a period of 28 years. Marked differences were found between ethnic groups. The highest incidence was among the Yemenite Jews, who reached an incidence of 18.5/105, followed by Ashkenazi Jews (10.0/105), non-Ashkenazi Jews, except Yemenites (7.3/105), and Arabs (2.9/105). In addition, it was found that in all Jewish subgroups, in contrast with the Arabs, there was a marked increase in incidence after 1985. CONCLUSIONS 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.