Low incidence of fatal coronary heart disease in Pima Indians despite high prevalence of non-insulin-dependent diabetes.

The incidence of fatal coronary heart disease (CHD) was determined in a population of Pima Indians from the Gila River Indian Community in Arizona. Between 1975 and 1984, 394 deaths occurred among 4,828 subjects aged 5 years or older, and 199 of these occurred in the 1,093 persons with non-insulin-dependent diabetes. Only 28 deaths were attributed to CHD; all occurred among the 689 diabetic persons 45 years of age or older. No CHD deaths occurred among the 419 nondiabetic subjects 45 years of age or older. The rate of fatal CHD among the diabetic subjects was higher in men than in women and increased with advancing age and duration of diabetes. A higher incidence of fatal CHD was associated with proteinuria, renal insufficiency, medial arterial calcification, diabetic retinopathy, insulin therapy, and an abnormal electrocardiogram. In Pima Indians aged 50-79 years, the incidence of fatal CHD was less than half that found in the Framingham population after controlling for age, sex, and diabetes (incidence rate ratio, 0.4; 95% confidence interval, 0.2-0.7). Factors protecting Pima Indians from fatal CHD may include racial heritage, low serum concentrations of total and low density lipoprotein cholesterol, and rarity of heavy smoking. Among the diabetic subjects, mortality from diabetic renal disease, which shows many of the same risk factors, may selectively compete and remove those at risk for fatal CHD. This would not, however, explain the lack of fatal CHD among the nondiabetic subjects. Fatal CHD shares many of the risk factors associated with the specific microvascular complications of diabetes, and diabetes and its associated attributes are the major predictors of fatal CHD in this population.