Moreover, results of the investigation show that this condition, known clinically as hypogonadism, is caused not by a defect in the testes, where testosterone is produced, but by improper functioning of the pituitary gland, which controls production of testosterone, or of the hypothalamus, the region of the brain that controls the pituitary.
"This starts a whole new story on the crucial complications of type 2 diabetes," said Paresh Dandona, M.D., senior author on the study and director of the Division of Endocrinology, Diabetes and Metabolism at the University at Buffalo and Kaleida Health, where the study was conducted.
Results of the study appear in the November issue of Journal of Clinical Endocrinology and Metabolism.
Sandeep Dhindsa, M.D., UB assistant professor of medicine and first author on the study, said the findings are important because hypogonadism has not been recognized as a complication of type 2 diabetes, and the high prevalence of 30 percent was unexpected.
"The surprisingly high prevalence of low testosterone levels was associated with lower levels of pituitary hormones called gonadotrophins, suggesting that the primary defect in these patients was either in the pituitary or higher up in the hypothalamus," he said. "Since gonadotrophins drive the testes to produce testosterone, this finding gives us an insight into the pathogenesis of this complication of type 2 diabetes."
Earlier studies, including those conducted by this research group, found that diabetic subjects with erectile dysfunction and low testosterone levels often have low levels of pituitary hormones. However, conclusions from prior studies have been fraught with problems with testosterone assays, Dhindsa noted.
Contact: Lois Baker
University at Buffalo