Previous exposure to hormone replacement therapy and confounders in metabolic studies

Objective: The quantity of intra-abdominal fat is highly associated with th e development of diabetes mellitus. We sought to determine whether recent h ormone replacement therapy (HRT) use modifies central fat and insulin sensi tivity in postmenopausal women compared with women who had never used HRT. Designs We measured intra-abdominal fat, subcutaneous abdominal fat, and sa gittal diameter at the L4-L5 vertebral disc space using computed tomography imaging. Total body fat and fat-free mass were measured using dual energy x-ray absorptiometry. Insulin sensitivity was assessed using the euglycemic hyperinsulinemic clamp technique in 42 nonobese postmenopausal women, age 51 +/- 4 years (12 recent HRT users plus 30 never-users). All women who wer e taking HRT discontinued it for 2 months before the study. Results: After statistical adjustment for age, previous use of HRT was asso ciated with decreased intra-abdominal fat (72 +/- 34 cm(2)) compared with n o HRT use (96 +/- 33 cm(2); p = 0.05). This difference remained significant after adjustment for time since menopause. When previous HRT users were co mpared with nonusers, there were no differences in subcutaneous abdominal f at, sagittal diameter, fat-free mass, total fat, insulin sensitivity, or bo dy weight. Conclusions: Recent HRT use is associated with lower intra-abdominal fat in nonobese, early postmenopausal women. This finding suggests a carry-over e ffect of HRT on intra-abdominal fat. Recent HRT use does not seem to be ass ociated with differences in glucose disposal.