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 non-diabetic African American men (N=61) and women (N=124), mean 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 triglyceride levels among tertiles of M.
Despite relatively low mean TG (87.8 ± 55.2 mg/dL), there were statistically significant correlations of M with TG (r = -.23, P<0.002), high density lipoprotein cholesterol (HDL-C; r =.19, P < 0.01)), and TG/HDL-C ratio (r = -.23, P<0.002). The correlations were strongest in men. Subjects with TG in an intermediate range (110-149 mg/dL) had insulin resistance equivalent to the high TG group (≥ 150 mg/dL).
In African Americans, triglyceride levels below the current metabolic syndrome threshold criterion are associated with insulin resistance.