Regional Body Composition Measured by Dual-Energy X-ray Absorptiometry (DXA) Relates to Insulin Resistance in a Sedentary Overweight and Obese Population DXA is a common tool for assessing body composition, with new capability to assess regional fat distribution. Using a cross-sectional design we evaluated the correlation between DXA regional body fat composition and insulin resistance in overweight/obese sedentary adults. DXA measures included fat free mass, visceral fat mass, visceral fat percent of total fat, android fat mass, and gynoid fat mass. Two indices of insulin resistance, HOMA-IR and Matsuda Index, were used. Linear correlation was tested using Pearson's correlation coefficient. Participants (n=68: 50 women/18 men) had mean age 28.8 ± 6.6 years and mean BMI 33.3 ± 7.1 kg/m2. Participants were categorized as insulin sensitive (mean ± SD: HOMA-IR 1.1 ± 0.4, Matsuda Index 8.3 ± 4.8) or insulin resistant (HOMA-IR 2.7 ± 2.0, Matsuda Index 3.6 ± 2.1). Of the DXA based body composition measures, visceral fat mass and visceral fat percent most consistently had a significant negative correlation (-0.30 to -0.48, P<0.05) with insulin resistance by Matsuda Index; this association was strongest in the insulin resistant group (R=-0.48, p<0.02). We conclude that DXA based measurement of visceral fat mass and percent of total fat could be used to predict insulin resistance by Matsuda Index in sedentary overweight/obese adults, reinforcing the expanding utility of DXA in clinical and research settings. Table 1. Correlation of Body Composition Measurements with HOMA-IR and Matsuda Index.