Free Testosterone and Sex Hormone-Binding Globulin Level in Type 2 Diabetic Men

Nam, Ki Deuk; Kim, Young Seol; Park, Cheol Young; Oh, Seung Joon; Kim, Deog Yoon; Woo, Jeong Taek; Kim, Sung Woon; Yang, In Myung; Kim, Jin Woo; Choi, Young Kil

Abstract

BACKGROUND: Insulin resistance is a risk factor for cardiovascular disease and type 2 diabetes mellitus. There are many previous studies indicating that insulin lowers serum sex hormone-binding globulin levels, and there is inverse correlation between insulin resistance and serum sex hormone-binding globulin levels in women. However, in men, a limited number of studies are available to explain the effect of sex hormone on age and insulin. Therefore, the present study was undertaken to investigate the relationship among free testosterone, hormone- binding globulin and age in type 2 diabetic men and control subjects. METHOD: Age, body mass index, total cholesterol, triglyceride, fasting blood sugar, and insulin concentrations were examined on 89 type 2 diabetic men and 47 control subjects. The free testosterone level was measured by commercially available double-antibody system (Radioimmunoassay). The sex hormone-binding globulin level was also measured by commercially available double-antibody system(Immunoradiometric assay).
RESULTS
1) Sex hormone-binding globulin level was significantly increased in patients with type 2 diabetes. However, there was no significant difference in free testosterone level between the two groups. 2) Sex hormone-binding globulin was positively correlated with age (r=0.4, p<0.001) in patients with type 2 diabetes. Sex hormone-binding globulin and free testos terone were not correlated with age in control sujects. 3) Free testosterone and sex hormone-binding globulin concentrations were not significantly related to serum insulin concentration after adjusting for age and body mass index.
CONCLUSIONS
We observed increased sex hormone-binding globulin concentration in diabetes man, and was a positively related to age. Further studies are needed to understand the relationships between age, insulin resistance, testosterone, and sex hormone-binding globulin concentrations.