Relationship between insulin and sex hormone-binding globulin levels during weight loss in obese women.

OBJECTIVE: The aim of this study was to assess the impact of insulin sensitivity on the relationship between sex hormone-binding globulin (SHBG) and insulin levels during active weight loss in euthyroid obese women. RESEARCH DESIGN AND METHODS: The study population comprised 80 premenopausal overweight and obese (BMI > or =27) women (mean age 41.44 +/- 10.03 years). Seventy patients were considered eligible for the study. Hypocaloric diets were given to all patients. Of 70 subjects who were initially willing to participate in the study, only 64 continued through to the last stage of the study. MEASUREMENTS: Anthropometric parameters, metabolic markers and sex hormone status were measured at baseline and on completion of the 12-week study period. RESULTS: Following the diet, significant decreases in insulin, homeostasis model assessment (HOMA) for insulin resistance and fasting glucose were noted. However, HOMA insulin secretion values did not change significantly. Interestingly, there was no significant correlation between SHBG and insulin levels at baseline. After weight loss, SHBG concentrations were significantly and negatively correlated with insulin levels. Therefore, it was concluded that, in severe insulin resistance, insulin does not inhibit the SHBG level. These findings could be important, but the authors have not found a similar relationship in the literature. CONCLUSION: The findings of this study provide some clues to the relationship between insulin and SHBG in insulin-resistant obese subjects. Insulin sensitivity or loss of fat tissue or leptin seem to be involved in the relationship between SHBG and insulin