Insulin resistance and dyslipidaemia in obese premenopausal and postmenopausal women matched for leg/trunk fat mass ratio

Objectives To investigate the influence of age, menopausal stage and selected hormonal factors on insulin resistance and dyslipidaemia in obese (BMI>30 kg/m²) pre‐ and postmenopausal women. Material and methods: Thirty‐ eight pre‐ and postmenopausal women were matched one by one for leg/trunk fat mass (FM) ratio. Body composition and regional FM by dual X‐ ray absorptiometry (DXA), fasting glucose, insulin and C‐ peptide, insulin resistance by homeostasis model assessment (HOMA‐ IR), insulin sensitivity by quantitative insulin sensitivity check index (QUICKI) and metabolic clearance rate (MCRestOGTT), insulin secretion (HOMAsecr), serum lipids, oestradiol, SHBG, testosterone and testosterone index (total testosterone/SHBG), free thyroxine, free triiodothyronine, cortisol and IGF‐ 1 were assessed. Results: HDL‐ cholesterol was higher (p=0.025) and total cholesterol/HDL‐ cholesterol ratio lower (p=0.026) in post‐ than in premenopausal women. No differences in parameters of insulin resistance or hormonal factors except oestradiol were found. In forward stepwise multiple regression analysis, cholesterol/HDL‐ cholesterol ratio was negatively predicted by age (R²=0.25, p=0.02) and HDL‐ cholesterol negatively (R²=0.16, p=0.013) predicted by belonging to the premenopausal group. MCRestOGTT was unfavourably predicted by IGF‐ 1 (R²=0.28, p=0.005) and testosterone (R²=0.36, p=0.048). Because of the relatively small number of subjects studied, interpretation of the results may to some extent have limited general validity. Conclusion: FM distribution is the major determinant of insulin resistance and dyslipidaemia, with only minor roles for menopausal status, age as such and age‐ related changes in hormonal factors in the regulation of glucose and lipid metabolism.