Glucose Tolerance, Body Stature, and Intramuscular Fat in African American Females

Sixty-six percent of African American women (AAW) are overweight or obese. This study examined the relations, if any, among body mass, glucose tolerance and thigh adipose in AAW. Twenty-six African American women (AAW) participated in this two-part study. One part involved a magnetic resonance image (MRI) of both thighs and the other an oral glucose tolerance test (OGTT). Subjects were classified into four groups; the first had Body Mass Index (BMI) less than 22.5, the second 22.5 to 24, the third 25 and 30 and the fourth greater than 30 kg/m². Intramuscular fat (IMF) and AAW have been examined in an older population and adolescent girls have received considerable exposure. Therefore, the college age years examined in this study are important times in assessing BMI, intramuscular-thigh fat and insulin resistance in AAW. Subjects were non-diabetic. The relation between IMF and plasma insulin was r2 = 0.60 at fasting, 0.92 at 60, 0.88 at 90 and 0.99 at 120 min after glucose ingestion in group 4. Relations between IMF and plasma insulin were also evident in groups 3 and 2, r2 = 0.3 and 0.2, respectively after 120 min of OGTT. Fat within knee extensor skeletal muscle related to glucose tolerance in AAW with a BMI between 22.5 and 25, 25 and 30 and above 30, suggesting type II diabetes may develop in large or obese AAW. Why these results occurred is not clear, however, they give a meaningful reason for AAW to maintain a reasonable body mass.