Glucocorticoid receptors (GR) and 3-O-methyl-D glucose (3-O-MG) transport were determined in mononuclear leukocytes (MNL) from 11 abdominal obese subjects, 10 pituitary-dependent Cushing's syndrome (Cushing's disease) and 10 healthy controls. Using a whole-cell competitive binding assay and H-3-dexamethasone as tracer, MNL of abdominal obese subjects were found to have 4855+/-1389 sites/cell which was significantly lower (p<0.05) than controls (6234+/-1568 sites/cell), although no significant difference was found in the mean serum cortisol level. Their mean Kd (affinity) was also significantly lower than that found in the healthy controls (obese Kd: 2.92+/-0.84nmol/l, control Kd: 4.55+/-0.67nM, p<0.05). On the other hand, the receptor characteristics in Cushing's disease patients were within the normal range. At the same time, 3-O-MG transport was determined in the same subjects. In Cushing's disease, 3-O-MG transport was within the normal range, whereas in abdominal obesity this value was significantly lower than the healthy controls (abdominal obese: 31.90+/-8.20; control: 46.26+/-12.91 fmol/10(6)cell. min, p<0.05). We also found a positive correlation between 3-O-MG transport and GR binding capacity in abdominal subjects (r=0.89, p<0.001), however we did not find such a correlation in Cushing's disease (r=0.60, p>0.05). These results indicated that, in abdominal obesity, the GR binding capacity in MNL is influenced by the changes in glucose transport. (J. Endocrinol. Invest. 21: 656-661, 1998) (C)1998, Editrice Kurtis.