About one third of men with type 2 diabetes show low levels of testosterone, and this is seems to be related to abnormal function of the pituitary gland - the master regulator of hormone production - according to a new study.

Although lower total testosterone levels have been reported in type 2 diabetics, the underlying cause has not been known, Dr. Paresh Dandona of the State University of New York at Buffalo and colleagues note in the Journal of Clinical Endocrinology and Metabolism.

Specifically, it has been clear whether the testes were somehow defective and unable to produce sufficient testosterone, or whether the underlying problem was a low level of the pituitary hormones that trigger testosterone secretion.

To investigate, the researchers studied 103 diabetic men who ranged in age from 28 to 80 years, and who had had type 2 diabetes for an average of 7.7 years.

A total of 33 percent of patients were found to have low testosterone. The team found that levels of two pituitary hormones - luteinizing hormone and follicle stimulating hormone - were also significantly lower in these men than in subjects with normal free testosterone levels.

In addition, Dandona and colleagues report that the higher the men’s body weight, the lower was their testosterone.

Given these findings, the researchers conclude that low testosterone is “a common defect in type 2 diabetes that requires further assessment.”

SOURCE: Journal of Clinical Endocrinology and Metabolism, November 2004.