Discriminating glucose tolerance status by regions of interest of dual- energy X-ray absorptiometry: Clinical implications of body fat distribution

OBJECTIVE - To determine whether measuring body fat distribution by dual-energy X-ray absorptiometry (DEXA) can be used to discriminate glucose tolerance status. RESEARCH DESIGN AND METHODS - Using a 75-g oral glucose tolerance test, a total of 1,015 Chinese subjects (559 men and 456 women) were categorized as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or diabetes. Blood pressure and lipid profiles of these subjects were measured. Waist-to-hip ratio (WHR) and DEXA were used to evaluate the varying patterns of body fat distribution among the groups. RESULTS - Body fat distribution, as reflected by WHR and the centrality index, showed significant partial correlation coefficients with glycosylated hemoglobin, blood pressure, and lipid profiles in all subjects. After adjusting for age and BMI, there were significant differences among the three glycemic groups for all the cardiovascular risk factors except for total cholesterol level. The diabetic group had a significantly higher WHR and centrality index, but lower femoral fat percentage than the NGT and IGT groups. The diabetic group also showed higher abdominal fat percentage than the NGT group. Moreover, the IGT group had a higher centrality index than the NGT group. However, no significant differences were found in the percentage of lean tissue mass among the three groups. Using multiple stepwise logistic regression models, the centrality index remained a significant factor for discriminating different glucose tolerance status independent of the percentage total body fat. CONCLUSIONS - Central obesity has shown significant correlation with cardiovascular risk factors among the three different glycemic groups. Centrality index measured by DEXA appears to be the better predictor of glucose intolerance, compared with WHR, abdominal fat, and general obesity (reflected by percentage total body fat or BMI) in a large cohort of the Chinese population.