The relation of central adiposity to components of the insulin resistance syndrome in a biracial US population sample.

The higher rates of type 2 diabetes mellitus, hypertension, and many others factors of the insulin resistant syndrome (IRS) often seen in African Americans compared to whites do not seem to be explained by differences in central obesity. Reasons for this may be due, in part, to the validity of the commonly used anthropometric surrogate of central adiposity. Recent findings have shown that waist circumference is a better surrogate of total body and visceral adipose tissue and is better correlated with CVD than the traditionally used anthropometric indexes of the body mass index or waist/hip ratios. In this study, waist circumference was employed to determine the association between central adiposity and components of the insulin resistance syndrome in blacks (N=1963) and whites (N=4894) from the US national population-based samples. Sex-specific correlation coefficients were used to estimate the association between waist circumference and factors of the IRS. Multiple linear regression analyses were used to determine racial differences in waist circumference and the independent association of waist circumference to some known factors of IRS adjusting for age, BMI, alcohol use, and smoking. Waist circumference was positively correlated with plasma glucose, DBP, SBP, LDL cholesterol, fasting insulin, serum triglyceride, total cholesterol and total cholesterol/HDL ratio in black and white men and women (P<0.01). In both biracial groups, waist circumference was significantly associated with increases in glucose, DBP, LDL cholesterol, total cholesterol, triglyceride and fasting insulin levels controlling for age, BMI, and behavioral risk factors, such as alcohol use and smoking (P<0.05). Our data shows that central adiposity assessed with waist girth did not wholly explain the higher prevalence of IRS components often seen among blacks. The results of this study reinforce the need to encourage the use of waist measure as a public health tool in screening for CVD risks.