Low SHBG independently predicts Type 2 diabetes in men
MedWire News: Low levels of sex hormone-binding globulin (SHBG) predict Type 2 diabetes in men, even after adjusting for testosterone levels, show study results.
Low levels of total testosterone and SHBG have previously been associated with an increased risk for Type 2 diabetes in men.
But Andre Araujo (New England Research Institutes, Inc., Watertown, Massachusetts, USA) and team note that, as “a substantial fraction of circulating testosterone is bound to SHBG,” it has been unclear whether SHBG influences the risk independently or via testosterone.
To investigate, the researchers conducted longitudinal analyses on 1128 men participating in the Massachusetts Male Aging Study who were aged 53.7 years on average and were free of diabetes at baseline and had a mean body mass index (BMI) of 27 kg/m2.
During an average follow-up of 13 years, 90 of the men were diagnosed with Type 2 diabetes.
Mean baseline SHBG, total, and free testosterone levels were 529.3 nmol/l, 529.3, and 11.8 ng/dl, respectively, in men who did not subsequently develop Type 2 diabetes, compared with a corresponding 26.0 nmol/l, 11.3, and 468.3 ng/dl in those who did.
Following adjustment for age, BMI, hypertension, smoking, alcohol intake, and physical activity, each one standard deviation (SD) decrease in SHBG doubled the relative risk for Type 2 diabetes. The association persisted after adjustment for both total and free testosterone.
Each one SD decrease in total testosterone increased the risk for Type 2 diabetes 1.29-fold, whereas free testosterone was not significantly associated with Type 2 diabetes.
“The implication of our findings is that the strategies for prevention of Type 2 diabetes should be directed at factors that determine SHBG rather than at raising testosterone levels,” conclude the authors in the Journal of Gerontology: Medical Sciences.
They add: “Further studies are needed to determine if SHBG can be used as a reliable marker to assess the efficacy of currently prescribed interventions, such as therapeutic lifestyle changes and/or pharmacological methods, aimed at preventing the development of Type 2 diabetes.”
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By Helen Albert