Ethnic differences in serum lipids and lipoproteins in overweight/obese African-American and white American women with pre-diabetes: significance of NMR-derived lipoprotein particle concentrations and sizes

Abstract

Objective: African-American women (AAW) suffer disproportionately from higher rates of cardiovascular disease (CVD) mortality compared with white American women (WAW), despite favorable lipid and lipoprotein profile. Therefore, we used nuclear magnetic resonance (NMR) to examine lipoprotein particle concentrations and sizes in overweight/obese AAW and WAW with pre-diabetes.

Participants and methods: We studied 69 AAW and 41 WAW, with mean age 46.5±11.3 years and body mass index (BMI) 37.8±6.4 kg/m(2). All participants completed standard oral glucose tolerance test (OGTT) and frequently sampled intravenous glucose tolerance test (FSIVGTT). Insulin sensitivity (Si) was calculated using MINIMOD method. Body composition was assessed using dual-energy X-ray absorptiometry (DEXA). Fasting blood was obtained for traditional lipids/lipoproteins and NMR-derived lipoprotein particle sizes and concentrations.

Results: We found that AAW with pre-diabetes were more obese (BMI 38.8±6.7 vs 36.0±5.4 kg/m(2), p=0.02) than WAW. Mean Si was not significantly different. However, the mean serum triglycerides were lower, whereas the high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (Apo A1) were significantly higher in AAW versus WAW. The large HDL particle concentration (6.1±3.1 vs 4.6±3.1 µmol/L, p=0.02) was significantly higher in AAW versus WAW. Mean total very low-density lipoprotein (VLDL) particle concentration was lower in AAW versus WAW (39.9±24.4 vs 59.2±25.6 nmol/L, p≤0.001). While mean total LDL particle concentrations were not different, mean small LDL particle concentrations were lower in AAW versus WAW (538.8±294.1 vs 638.4±266 nmol/L, p=0.07).

Conclusions: We found a more favorable NMR-derived lipoprotein profile in AAW that extends the traditional antiatherogenic lipid/lipoprotein profiles. Clinically, these favorable lipid/lipoprotein profiles cannot explain the paradoxically higher CVD mortality in AAW than WAW and warrant further prospective outcome studies.

Keywords: Lipoprotein Subclasses; Obesity; Racial Differences; Women.