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martes, 20 de diciembre de 2011
Low Testosteron may affect insulin sensitivity
Low Testosterone May Affect Insul
By Kristina Fiore, Staff Writer, MedPage Today Published: December 08, 2011
NEW YORK -- It's not just about diminished libido; low testosterone may also have effects on insulin sensitivity, research indicates. Several studies have shown that men with low testosterone are more likely to have metabolic troubles, including decreased insulin sensitivity, Bradley Anawalt, MD, of the University of Washington Medical Center in Seattle, said during a press briefing here, arranged by the Endocrine Society. Much work has linked low serum testosterone levels among men in the general population with metabolic syndrome -- of which insulin resistance is a key component. Other studies have shown that low levels of the hormone are particularly common in men with type 2 diabetes, and some have even found it to be common in type 1 disease. Still other studies show that in men with prostate cancer, androgen deprivation therapy, which reduces levels of all androgens in the body, including testosterone, also decreases insulin sensitivity. In one recent study, however, sex hormone-binding globulin -- but not testosterone alone -- was associated with an increased risk of metabolic syndrome, researchers reported. Mathis Grossmann, MD, PhD, of the University of Melbourne in Australia, who wasn't at the briefing but has conducted several studies on testosterone and its metabolic effects, told MedPage Today that the hormone's effects on body composition are likely the main mediator of the relationship between low levels and insulin sensitivity. Adequate testosterone levels increase muscle mass and decrease fat mass, Grossmann said, and that has important metabolic effects. Researchers, then, have long speculated whether giving testosterone to patients with metabolic syndrome or type 2 diabetes could improve their metabolic parameters. Some studies have concluded that the therapy "may represent an important avenue for intervention," but Grossmann said it first needs to be studied in larger, randomized controlled trials. "Although testosterone increases muscle and decreases fat, changes that would be favorable to insulin sensitivity, any positive effect from testosterone is likely to be small in most men with low testosterone levels," Anawalt told MedPage Today. "The exception to this," he said, "is men with very, very low levels of testosterone, such as those who are surgically or medically castrated. In these men, restoring testosterone levels might have more meaningful effects on glucose metabolism and insulin sensitivity." However, he said that hypogonadism treatments, overall, probably aren't a "promising treatment for improving glucose levels in men with diabetes." In the meantime, he said, clinicians recommend that men with both type 2 diabetes and low levels of testosterone should try to improve their metabolism via lifestyle changes such as weight loss and exercise.