It is generally thought that in Japanese the incidence of cerebrovascular diseases was formerly high and the incidence of ischemic heart diseases and diabetes low (Kays et al., 1966; WHO, 1980), but that recent westernisation of the Japanese life style, particularly diet, has brought changes. To clarify the influences of westernisation of life style on diseases in Japanese, in a recent survey Japanese-Americans, in whom westernisation of life style occurred earlier and more intensively, were compared with Japanese living in Japan, where these changes have been later and less pronounced.

The survey of Japanese-Americans was started in 1970 in Hilo City and Kona District, Hawaii. In 1978, the survey in Los Angeles was started. The results of the first of these surveys of Japanese-Americans, and of Japanese in Hiroshima Prefecture, have already been reported (Kawate et al., 1979). This paper reports the results of subsequent surveys in Hawaii, Los Angeles and Hiroshima, placing emphasis on the characteristics of diabetes mellitus among Japanese-Americans.

Background of Japanese migrants and their offspring

Emigration of Japanese to Hawaii began around 1885 in reply to the request from the Hawaiian Dynasty of those days to alleviate the shortage of labour for the sugar cane plantations. After World War II, the social status of these migrants improved sharply. At present, second- and third-generation Japanese-Americans are active in various occupations in Hawaii. In Hilo City on the island of Hawaii where the survey was conducted, 14,000 Japanese-Americans live, exceeding the population of white Americans in that city. The Japanese migrants living in Hilo City came from various prefectures of Japan, and have organised societies of people from each prefecture.