Diabetes and Impaired Glucose Tolerance in Three American Indian Populations Aged 45-74 years: The Strong Heart Study

The purpose of this study is to estimate the prevalence rates of diabetes and impaired glucose tolerance (IGT) in 3 American Indian populations using standardized diagnostic criteria, and to assess the association of diabetes with the following selected possible risk factors: age, obesity, family history of diabetes, and amount of Indian ancestry. This cross-sectional study involved 13 American Indian tribes and communities in Arizona, Oklahoma, North Dakota and South Dakota. Eligible participants were invited to a clinic for a personal interview and a physical examination. Diabetes and IGT status were defined by the World Health Organization criteria and were based on fasting plasma glucose and oral glucose tolerance test results. Data on age, family history of diabetes, and amount of Indian ancestry were obtained from personal interviews. Diabetes status was determined for 4,304 eligible study participants. In all 3 centers, diabetes was more prevalent in women than men. Arizona had the highest age-adjusted rates of diabetes. Diabetes rates in Oklahoma and the Dakotas, were several times higher than those reported for the U.S. population. Rates of IGT among the 3 populations were similar to those in the U.S. population. Diabetes rates were positively associated with age, level of obesity, amount of Indian ancestry, and parental diabetes status. Diabetes is found in epidemic proportions in American Indian populations. Prevention programs and periodic screening should be implemented among American Indian populations. The Indian Health Service has developed standards of care and intervention for individuals diagnosed with diabetes. These programs should be expanded to include those with IGT to improve glycemic control or to reduce risk of development of diabetes as well as to reduce risk of diabetic complications.