Plasma lipid concentrations in nondiabetic African American adults: associations with insulin resistance and the metabolic syndrome

Abstract

Despite higher rates of cardiovascular disease, African Americans have a more favorable lipid profile. The purpose of the study was to examine the association between plasma lipid concentrations and insulin resistance in African Americans and to determine if insulin resistance is present at a lower triglyceride (TG) threshold than is used for metabolic syndrome criteria. Data were examined on 185 nondiabetic African American men (n = 61) and women (n = 124), mean age, 39.8 years. Measurements included blood pressure, anthropometrics, oral glucose tolerance test, and insulin sensitivity ( M) by insulin clamp. The relationship between lipids and insulin sensitivity was analyzed by correlation analysis and by comparing TG levels among tertiles of M. Despite relatively low mean (± SD) TG level (87.8 ± 55.2 mg/dL), there were statistically significant correlations of M with TG ( r = −0.23, P < .002), high-density lipoprotein cholesterol (HDL-C; r = 0.19, P < .01), and TG/HDL-C ratio ( r = −0.23, P < .002). The correlations were strongest in men. Subjects with TG in an intermediate range (110-149 mg/dL) had insulin resistance equivalent to that of the high-TG group (≥150 mg/dL). In African Americans, TG levels below the current metabolic syndrome threshold criterion are associated with insulin resistance.