Role of deep abdominal fat in the association between regional adipose tissue distribution and glucose tolerance in obese women

Computed tomography (CT) was used to study the association between adipose tissue localization and glucose tolerance in a sample of 52 premenopausal obese women aged 35.7 +/- 5.5 yr (mean +/- SD) and with a body fat of 45.9 +/- 5.5%. Body-fat mass and the body mass index (BMI) were significantly correlated with plasma glucose, insulin, and connecting peptide (C-peptide) areas after glucose (75 g) ingestion (.40 less than or equal to r less than or equal to .51, P less than .01). Trunk-fat accumulation and the size of fat cells in the abdomen displayed highly significant correlations with postglucose insulin levels. The C-peptide area was also positively correlated with abdominal fat cell size (r = .76, P less than .01) and was more closely associated with the sum of trunk skin folds (r = .59, P less than .001) than with the extremity skin folds (r = .29, P less than .05). Subcutaneous and deep-abdominal-fat areas measured by CT displayed comparable associations with the plasma insulin area (r = .44 and .49, respectively; P less than .001) but marked differences in the associations with glucose tolerance. Indeed, subcutaneous abdominal fat was not significantly correlated with the glucose area, whereas deep abdominal fat showed a significant correlation (r = .57, P less than .001) with the glucose area. Midthigh fat deposition measured by CT was not, however, correlated with plasma glucose, insulin, or C-peptide areas. Partial correlation analyses indicated that the effect of accumulation of deep abdominal fat on glucose tolerance was independent from total adiposity and that no association was observed between total adiposity and glucose tolerance after control for accumulation of deep abdominal fat. These results emphasize the importance of deep abdominal fat as an independent correlate of glucose tolerance in obese women.