INCIDENCE OF TYPE-I DIABETES IN PEOPLE UNDER 30 YEARS OF AGE IN BARBADOS, WEST-INDIES, 1982-1991

OBJECTIVE- To determine the incidence of type I diabetes among individuals <30 years of age on the island of Barbados in the Caribbean. The population is predominantly African in origin but exhibits a relatively westernized lifestyle. RESEARCH DESIGN AND METHODS- Cases occurring during the years 1982-1991 were drawn from records at Queen Elizabeth Hospital and from physicians treating insulin-dependent diabetes mellitus (IDDM) patients. Patients using insulin and <30 years of age at onset were included. Ascertainment was estimated at 94%. RESULTS- The average annual incidence of type I diabetes among Barbadians was 4.1/100,000 when age-adjusted to the world's population. There were 59 incident cases during this 10-year interval. The risk for males was 4.4 and for females 4.0/100,000. Among those 0-14 years of age, the risk was 5.0/100,000. Mean age at onset (+/- SD) was 14.7 +/- 6.9 for males and 12.5 +/- 5.7 for females. Males showed marked seasonal variation in risk and a more than threefold increase in annual incidence during 1984-1985. In contrast, females exhibited a stable pattern of IDDM risk during the 10-year interval. CONCLUSIONS- The incidence rate in Barbados falls near the lower limits of rates reported for Caribbean populations. There was a marked seasonal effect among males, even though the climate varies little throughout the year. This observation, and the incidence peak during 1984-1985, provide support for the role of environmental factors in the etiology of IDDM.