Insulin resistance and androgens in healthy women with different body fat distributions.

Objective: To compare androgens and sex hormone-binding globulin (SHBG) levels, and indices of insulin sensitivity (the response of plasma insulin and C-peptide in OGTT, insulin resistance and beta-cell activity estimated with the homeostasis assessment model (HOMA model) in healthy obese premenopausal women with different body fat distributions.

Patients And Methods: Free testosterone, androstenedione, SHBG levels and responses of plasma glucose, insulin and C-peptide in OGTT were examined in 74 healthy premenopausal women (19 with lower-body obesity (WHR < 0.80), 20 with pure abdominal obesity (WHR > 0.85), 19 with predominant abdominal obesity (WHR 0.81-0.85) and 18 normal-weight women). Insulin resistance and beta-cell function were estimated with the HOMA model.

Results: Both fasting and glucose-induced insulin levels were higher in women with pure abdominal obesity than in the controls (p < 0.001) and in those with lower-body obesity (P < 0.01). Insulin resistance was also higher in women with pure abdominal obesity than in the controls (p < 0.01) and those with lower-body obesity (p < 0.05). Free testosterone (p < 0.01) was higher and SHBG (p < 0.001) was lower in women with abdominal obesity than in the control group and those with lower-body obesity. Insulin significantly correlated with SHBG, and this correlation was independent of androgens, obesity and obesity type. Beta-cell function positively correlated with free testosterone, whereas insulin resistance negatively correlated with SHBG, and was independent of obesity and obesity type.

Conclusions: In healthy premenopausal women, increased BMI and more pronounced abdominal fat accumulation was associated with increased androgenic activity (higher free testosterone and lower SHBG levels) and with insulin resistance estimated using the HOMA model, as well as with increasing basal and glucose-induced insulin levels. SHBG levels correlated with insulin and insulin resistance independently of the degree of obesity, obesity type and androgens, whereas beta-cell function correlated only with free testosterone.