Testosterone, sex hormone-binding globulin inversely linked with metabolic syndrome in Korean men

Testosterone and sex hormone-binding globulin both demonstrated an inverse association with metabolic syndrome in men, researchers in Korea reported.

“The metabolic syndrome is estimated to affect approximately 25% of the adult population, and its prevalence continues to rise worldwide,” Yun-Mi Song, MD, MPH, PhD, professor in the department of family medicine at Samsung Medical Center, Sungkyunkwan University, Seoul, and colleagues wrote. “There is accumulating evidence that low testosterone and sex hormone-binding globulin levels are associated with [metabolic syndrome] in men. Exact mechanisms underlying the association between testosterone and metabolic syndrome are still very poorly understood.”

The researchers performed a cross-sectional, community-based study of 1,098 men, including 139 pairs of monozygotic twins. Song and colleagues used linear mixed models and generalized estimating equation models to analyze associations between sex hormones and metabolic syndrome.

After researchers adjusted for covariates, such as physical exercise, alcohol consumption and smoking, a 1-standard deviation increase in total testosterone was linked with a 31% decreased risk for metabolic syndrome as defined by the National Cholesterol Education Program-Third Adult Treatment Panel (NCEP-ATP III) criteria, Song and colleagues reported, and a 29% decreased risk according to International Diabetes Federation (IDF) criteria. Meanwhile, a 1-standard deviation increase in sex hormone-binding globulin was associated with a 48% decreased risk for metabolic syndrome per NCEP-ATP III and a 50% decreased risk per IDF criteria.

Sex hormones were inversely associated with a variety of components of metabolic syndrome, including high blood pressure, according to a metabolic component-specific analysis, the researchers wrote. Total testosterone was inversely linked with abdominal obesity, high blood pressure and low HDL. Free testosterone was inversely associated with high blood pressure and abdominal obesity, and sex hormone-binding globulin was inversely linked with all components of metabolic syndrome except for high blood pressure, they wrote.

Among twins, researchers reported that within-pair differences in total testosterone and sex hormone-binding globulin levels were inversely correlated with differences in waist circumference.

“In conclusion, this study showed that serum testosterone and [sex hormone-binding globulin] were inversely associated with [metabolic syndrome] and many of its components,” the researchers wrote. “After having controlled both genetic and shared familial-environmental influences in the co-twin control study, only waist circumference was significantly associated with the sex hormones. These findings suggest that unshared unique environmental effects significantly contribute to the association between testosterone and [sex hormone-binding globulin] and abdominal obesity. More longitudinal studies to determine causality and further researcher to elucidate genetic and unshared environmental influences in the association between sex hormones and [metabolic syndrome] are warranted.” – by Andy Polhamus

Disclosure: The researchers report no relevant financial disclosures.