The effect of Indian or Anglo dietary preference on the incidence of diabetes in Pima Indians.

OBJECTIVE In short-term studies, adoption of a traditional diet is associated with reduction in metabolic abnormalities often found in populations experiencing rapid lifestyle changes. We examined the long-term effects of a self-assessed traditional or nontraditional dietary pattern on the development of type 2 diabetes in 165 nondiabetic Pima Indians. RESEARCH DESIGN AND METHODS Dietary intake was assessed in 1988 by a quantitative food frequency method, and subjects were asked to classify their diet as "Indian," "Anglo," or "mixed." The Indian diet reflects a preference for Sonoran-style and traditional desert foods. The Anglo diet reflects a preference for non-Sonoran-style foods typical of the remaining regions of the U.S. RESULTS In women, the intake of complex carbohydrates, dietary fiber, insoluble fiber, vegetable proteins, and the proportion of total calories from complex carbohydrate and vegetable proteins were significantly higher (P < 0.05) in the Indian than in the Anglo diet. The mixed diet was intermediate in of all these constituents. In men, the intake for these nutrients was also higher in the Indian than in the Anglo group, but not significantly. Diabetes developed in 36 subjects (8 men and 28 women) during 6.2 years of follow-up (range 0.9-10.9). The crude incidence rates of diabetes were 23. 35, and 63 cases per 1,000 person-years in the Indian. mixed, and Anglo groups, respectively. After adjustment for age, sex, BMI, and total energy intake in a proportional hazards model, the risk of developing diabetes in the Anglo-diet group was 2.5 times as high (95%) CI 0.9-7.2) and the rate in the mixed-diet group was 1.3 times as high (0.6-3.3) as in the Indian-diet group. CONCLUSIONS This study suggests that the adoption of an Anglo diet may increase the risk of developing diabetes in Pima Indians, but it does not provide unequivocal evidence for or against this hypothesis.