Characterization of metabolically unhealthy overweight/obese African American women: significance of insulin-sensitive and insulin-resistant phenotypes.

Background: Obesity is often associated with high cardiovascular disease risk factors. Obesity is common in African American women. We investigated the characteristics of metabolically healthy and metabolically unhealthy overweight/obese African American women based on the presence of insulin resistance.

Materials/methods: We studied 196 apparently healthy overweight/obese African American women with family history of type 2 diabetes. Waist circumference, fasting glucose, insulin, c-peptide, lipids and lipoproteins, and systolic and diastolic blood pressure were obtained in each subject. In addition, insulin sensitivity was calculated using Bergman's Minimal Model Method. We defined insulin-sensitive metabolically healthy African American women as individuals with insulin sensitivity greater than 2.7 x 10(-4) x min(-1) (uU/ mL)(-1) and insulin resistant, metabolically unhealthy as insulin sensitivity less than 2.7 x 10(-4) x min(-1) (uU/mL)(-1).

Results: Thirty-three percent of our subjects were metabolically healthy African American women, while 67% were metabolically unhealthy African American women. The metabolically healthy subjects were significantly younger and less obese than the metabolically unhealthy subgroup. Mean fasting serum glucose, insulin, and c-peptide were significantly lower (P = .001) in the metabolically healthy than in metabolically unhealthy subjects. However, the mean blood pressures were within normal in both subgroups. Mean serum cholesterol (p < .05) and triglyceride (p < .001) levels were significantly lower, whereas high-density lipoprotein cholesterol (p < .03) was significantly higher in the metabolically healthy than in the metabolically unhealthy subjects. We found 25.5% of our subjects had metabolic syndrome (30.3% metabolically unhealthy and 15.6% metabolically healthy).

Conclusion: We concluded that: (1) despite obesity, metabolically healthy African American women appear to be less prone to type 2 diabetes and cardiovascular disease and (2) in view of the higher prevalence of metabolic syndrome, metabolically unhealthy African American women should be targeted for primary prevention of type 2 diabetes and cardiovascular disease.