Objectives: an increasing interest is being focused on the role of the somatotropic axis in the modulation of body weight and fat distribution, particularly in climacteric women. The influence of the glycometabolic state on the somatotropic axis in postmenopausal and in obese subjects has not been investigated. The aim of the present study is to evaluate whether menopause and body mass index (BMI) affect the response of growth hormone (GH), insulin-like growth factor-binding protein-1 (IGFBP-1) and -3 (IGFBP-3) to the oral glucose tolerance test (OGTT).
Methods: the study included 24 women, aged 45-55 years, categorized into 4 groups, premenopausal pre-obese (BMI = 28.5 +/- 0.8 Kg/m2) and normal body weight (BMI = 22.2 +/-1.1 Kg/m2), and postmenopausal pre-obese and normal body weight. All women underwent: (1) a biophysical evaluation with determination of waist/hip ratio; (2) an assessment of fat and lean tissue mass and body fat distribution by total body DEXA; and to (3) an OGTT.
Results: in response to OGTT plasma GH levels significantly decreased in all groups, but the relative decrease was more prominent in the lean subjects. A significant decrease of IGFBP-1 levels in response to OGTT was observed in all women, regardless of menopausal age and BMI, while IGFBP-3 levels did not significantly change in either group.
Conclusions: in conclusion, the impact of both BMI and menopausal condition on GH, IGFBP-1, and -3 response to OGTT is limited to a blunted GH response in overweight women compared with normally-weighing ones. These findings appear to rule out the hypothesis that a common glycometabolic derangement may affect both the modifications of body weight and of the somatotropic axis observed in perimenopausal women.