PREVALENCE OF DIABETES AND IMPAIRED GLUCOSE-TOLERANCE AMONG NAVAJO INDIANS

OBJECTIVE - To estimate the prevalence of diabetes mellitus and impaired glucose tolerance and the incidence of clinically diagnosed diabetes in a community of Navajo Indians. RESEARCH DESIGN AND METHODS - We conducted a survey of a representative Navajo community screened for diabetes 3 yr previously. We used 75-g oral glucose tolerance tests to determine the prevalence of diabetes mellitus and impaired glucose tolerance and conducted medical record reviews to identify cases of diabetes that were diagnosed during routine medical care after the earlier study. RESULTS - By World Health Organization diagnostic criteria, the age-adjusted diabetes prevalence among 419 Navajo Indians 20-74 yr of age was 13.9% (95% confidence interval [CI] 9.2-18.5) for men and 18.4% (95% CI 14-22.8) for women. The ratio of the prevalence of diabetes among the Navajo population studied to that in the general United States population was 2.5. The prevalence of impaired glucose tolerance was 8% (95% CI 3.3-12.7) among men and 12.9% (95% CI 7.9-17.9) among women. Based on clinical diagnoses of diabetes made during routine medical care, mean +/- SE age-adjusted incidence of diagnosed diabetes among men was 8.6 +/- 4.3/1000 person-yr and 11.1 +/- 4.4/1000 person-yr among women. CONCLUSIONS - Although lower than that of some other tribes, the prevalence of diabetes among Navajo Indians is substantially higher than that in the general U.S. population. The high rate of clinical diagnoses suggests that the prevalence of the disease may continue to rise.