It is well known that abdominal visceral fat is closely related to insulin resistance in adult subjects. But few reports have evaluated the relationship between abdominal fat and insulin resistance in obese children using MRI or CT scanning. The purpose of this study was to investigate the sex difference in abdominal fat distribution (AFD) and insulin resistance in obese children. The subjects were 66 obese children (38 boys, and 28 girls) with a mean age of 10.9 years (7-17 years) and a mean relative weight (RW) of 152.9%. Abdominal subcutaneous fat (ASF) and visceral fat (AVF) were measured using L4-L5 CT scanning. The 3-h (Pre, 30, 60, 120, and 180min) oral glucose tolerance test (OGTT) was performed, and we regarded the insulin area-under-the-curve (AUC) as an index of insulin resistance. There was no significant difference in ASF between boys and girls (253.3 vs 268.0cm²), but AVF was significantly larger in boys than in girls (57.8 vs 43.7cm²: p < 0.05). The insulin AUC was significantly greater in girls than in boys (10652.1 vs 6922.3uU min/ml: p < 0.001). The simple correlation of both ASF and AVF with insulin AUC in both sexes was significant. After controlling for the total adiposity (RW) by partial correlation, the relationship between AFD and insulin AUC disappeared in girls, but remained in boys. These data suggest that total body fat, rather than abdominal fat, may be the primary determinant of insulin resistance in girls. On the other hand, in boys the abdominal fat depot, especially AVF, is associated with insulin resistance independent of total body fat level.

DESCENTE SPORTS SCIENCE Vol.27/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE