Study of Sex Hormone-Binding Globulin in Type 2 Diabetes Mellitus

Background: Sex hormone-binding globulin (SHBG) regulates the levels of free sex hormones by sequestering circulating sex hormones and participates in some of the biological actions of sex hormones by mediating cellular uptake. Low circulating levels of sex hormone–binding globulin are a strong predictor of the risk of type 2 diabetes in women and men. However, it has been difficult to determine whether biomarkers such as SHBG can predict the risk for type 2 diabetes because of the complicated relationships between sex hormones and other risk factors for type 2 diabetes mellitus (T2DM), including hyperglycemia and insulin resistance. SHBG has emerged as one of the multiple genetic and environmental factors that potentially contribute to the pathophysiology of T2DM. Objective: To study the blood level of SHBG in T2DM and to determine its potential role in pathogenesis of diabetes mellitus. Material and Methods: In this case-control study, 40 women aged 35-65 classified to (20 postmenopausal and 20 premenopausal) with newly diagnosed type 2 diabetes mellitus (T2DM) were randomly selected and compared with 10 non-diabetic as control. Twenty men aged 37-65 with T2DM were randomly selected and compared with 10 nondiabetic men as control. Plasma levels of (SHBG), total and free testosterone were measured. The two groups were matched for their ages, body mass index (BMI) and Waist circumference. After complete observation and examination, insulin level, fasting blood glucose, 2-hpp glucose, HbA1c were measured. Also, total cholesterol, HDL-cholesterol, triglyceride, systolic and diastolic BP was measured. Results: Among men, higher plasma levels of SHBG than women were prospectively associated with a lower risk of type 2 diabetes. The mean serum level of SHBG was 13.9±11.2 nmol/l in diabetic patients and 9.1±4.1 nmol/l in non-diabetic subjects which was non-significantly different (P > 0.05). There was a significant correlation between age and SHBG. On the other hand, there was nonsignificant correlation between SHBG with HOMA and insulin level, and no correlation with other parameters in female premenopausal diabetic group. Also, there was non significant correlation between SHBG and insulin level and BMI and no correlation with other parameters in female postmenopausal diabetic group. SHBG have strong relationship with BMI and waist circumference, this relation is found to be a slightly negative correlation between SHBG, BMI and waist circumference in preand postmenopausal but there is no significant correlation between the same variable in men. Conclusion: Throughout this study even if increased SHBG may be associated with increased insulin resistance or associated with some etiological factors of type 2 diabetes mellitus, it can’t be concluded to be a direct predictor of type 2 diabetes mellitus. [Hatem M. Salem, Khaled M. Hadhoud, Mohamed S. S. Saad, and Ahmad Baraka. Study of Sex Hormone-Binding Globulin in Type 2 Diabetes Mellitus. Journal of American Science 2011; 7(12):1266-1272]. (ISSN: 1545-1003). http://www.americanscience.org. 157