Prevalence and correlates of the insulin resistance syndrome among Native Americans. The Inter-Tribal Heart Project

The clustering of factors characterizing the insulin resistance syndrome has not been assessed among Native Americans, a population at high risk for diabetes and cardiovascular disease. We examined the distribution and correlates of the insulin resistance syndrome among individuals in three Chippewa and Menominee communities in Wisconsin and Minnesota.

Cross-sectional data from 488 men and 822 women ages > or = 25 years in the Inter-Tribal Heart Project (1992-1994) were included. The clustering of each individual trait (hypertension, diabetes, high triglycerides, and low HDL cholesterol) with the other traits and the association of the number of traits with measures of adiposity and insulin levels were examined.

Among the men, 40.4, 32.6, 17.4, and 9.6% had none, one, two, or at least three of the four traits, respectively; among the women, the respective percentages were 53.2, 25.6, 15.3, and 6.0%. The percentage of individuals with each particular trait significantly increased (P < 0.01) among those with none, one, or at least two other syndrome traits. Having more syndrome traits was significantly related (P < 0.001) to higher BMI, conicity index, waist circumference, and waist-to-hip and waist-to-thigh ratios. Among individuals with normal glucose levels, having more syndrome traits was significantly related (P < or = 0.05) to higher fasting insulin levels after adjusting for age and measures of adiposity, although associations were attenuated with adjustment for either BMI or waist circumference.

Traits characterizing the insulin resistance syndrome were found to be clustered to a significant degree among Native Americans in this study. Comprehensive public health efforts are needed to reduce adverse levels of these risk factors in this high-risk population.