BOSTON — Normal-weight African American women were twice as likely to have insulin resistance as were similarly lean white and Hispanic women, based on the findings of an epidemiologic study.
In addition, unlike their white and Hispanic counterparts, African American women's increasing body mass index levels only minimally influenced their prevalence rate of insulin resistance, Dr. Jennifer Wolfgang said at the annual meeting of the Endocrine Society.
Race “may be an important independent risk factor for insulin resistance and potentially type 2 diabetes and heart disease,” said Dr. Wolfgang of Wake Forest University, Winston-Salem, N.C. Weight-based screening standards may need to be adjusted so that even lean African American women are evaluated for insulin resistance, diabetes, and cardiovascular disease.
Dr. Wolfgang and her colleagues reviewed the data for participants in the multicenter Insulin Resistance Atherosclerosis Study, which was designed to evaluate the relationships between the degree of insulin sensitivity and variables associated with cardiovascular disease.
The approximately 1,600 men and women—all of whom were in general good health and without diabetes or impaired glucose tolerance—were divided by sex and placed into quartiles according to body mass index (BMI): less than 25, 25–30, 30–35, and greater than 35 kg/m
After correction for age and recruitment sites, the difference in prevalence rates for African Americans, compared with whites and Hispanics, remained statistically significant, Dr. Wolfgang said. For the other three quartiles, the women had similar risk for insulin resistance across all three ethnic groups.
A similar trend was observed for African American men, but the differences were not statistically significant.
Dr. Wolfgang speculated that the ethnic disparities might be a consequence of between-race differences in the percentage or distribution of intraabdominal fat. Some yet-to-be-identified genetic variation also could be the source of the differences, she noted.
There is no simple clinical method for routinely measuring insulin resistance, Dr. Wolfgang acknowledged, but the observation of insulin resistance at low BMI levels in African American women argues for aggressive management of the more easily measured cardiovascular risk factors, such as high blood pressure, high cholesterol levels, and high blood glucose values.
Dr. Wolfgang reported no conflict of interest with respect to her presentation.
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