Incidence of hypertension and non-insulin dependent diabetes mellitus and associated risk factors in a rapidly developing Caribbean community: the St James survey, Trinidad.

OBJECTIVE: To compare the incidence rates of hypertension and non-insulin dependent diabetes mellitus in relation to ethnicity and other characteristics in a rapidly developing community.
DESIGN: Prospective surveillance of a total community for five years.
SUBJECTS: Cohort of 2491 men and women aged 35 to 69 years (79% response), of African, Indian and "other' (mainly Afro-European) descent.
RESULTS: During surveillance, secular increases occurred in fasting blood glucose concentrations in both sexes and in body mass index (BMI) in men, with apparent secular reductions in systolic blood pressure in both sexes. Incidence rates of hypertension did not differ significantly with ethnicity, ranging between 33 and 41 per 1000 person-years in men and between 27 and 32 per 1000 person-years in women. In men, the incidence of diabetes (per 1000 person-years) in Indians (24) was significantly higher than in Africans (13) and others (11). In women, the diabetic incidence was similar to that for men in Indians (23) and Africans (14), but in others was twice that in men (21). In both sexes, weight gain was an important risk factor for hypertension, whereas risk of diabetes increased with BMI at baseline. The increased risk of diabetes in Indians among men was independent of baseline BMI and blood glucose.
CONCLUSION: Apart from the increased risk of diabetes in Indians, ethnicity had no significant influence on incidence rates of hypertension and diabetes in Trinidad. Secular increases in blood glucose in both sexes and in BMI in men probably contributed to the concurrent increase in mortality from coronary heart disease in this community.