Sex Hormone Protein May Predict Type 2 Diabetes

Aug. 6 -- WEDNESDAY, Aug. 5 (HealthDay News) -- A protein that carries and activates sex hormones throughout the body may also predict those at high risk of developing type 2 diabetes, a new study finds.

The protein, called sex hormone-binding globulin (SHBG), regulates the levels of testosterone and estrogen in the blood. Researchers suspect it also plays a role in the development of type 2 diabetes.

"Basically, we have identified plasma SHBG as a strong and significant marker for type 2 diabetes development in initially healthy men and women," said lead researcher Dr. Simin Liu, professor and director of the Center for Metabolic Disease Prevention in the School of Public Health at the University of California Los Angeles, David Geffen School of Medicine.

Low levels of SHBG were a significant predictor for the risk of development of type 2 diabetes, the researchers found.

"To our knowledge, there are few biomarkers for type 2 diabetes prediction that have presented both genetic and plasma phenotypic evidence like ours," Liu said.

The report was published in the Aug. 5 online edition of the New England Journal of Medicine.

For the study, Liu's group looked at SHBG levels in 718 postmenopausal women -- 359 with type 2 diabetes and 359 without -- who participated in the Women's Health Study, a large-scale cardiovascular trial begun in 1993. In a separate investigation, they confirmed their findings in a group of 340 men who participated in the Physicians' Health Study II, a similarly large study.

Besides the inverse relationship between levels of SHBG and type 2 diabetes, they identified two genetic variants in the gene coding for SHBG -- one increases type 2 diabetes risk while the other decrease diabetes risk.

"Plasma SHBG appeared to predict type 2 diabetes risk beyond traditional risk factors," Liu said. "In direct comparison, it significantly outperformed some newer risk predictors such as HbA1c (glycated hemoglobin) and C-reactive protein."