BARCELONA — Consider measuring testosterone levels in all male type 2 diabetes patients with symptoms of hypogonadism, Dr. Eric Meuleman of the Free University Medical Center, Amsterdam, advised at an international congress on prediabetes and metabolic syndrome.
Untreated hypogonadism can cause substantial distress and social consequences to the men involved, he noted. “People lose jobs and marriages over low testosterone. It is generally something that has been ignored in the past.”
Reductions in testosterone levels happen to all men as they get older, with concentrations dropping by an average of 1% per year after age 50 (J. Clin. Endocrinol. Metab. 2007;92:196–202). Between the ages of 40 and 79 years, 12.3% of men have testosterone levels low enough to produce clinical signs and symptoms such as diminished sexual desire, poor erectile quality, low energy, reduced sense of vitality, and anemia, Dr. Meuleman said. But men with type 2 diabetes seem to be more susceptible to testosterone loss, with an estimated 33% of this group affected by the condition.
Because the symptoms are fairly nonspecific, the syndrome is difficult to diagnose and may not appear to be separate from the effects of diabetes. The Endocrine Society issued guidelines last year on treating symptoms of hypogonadism (low testosterone), listing drops in libido, muscle bulk, and height—along with hot flushes, loss of body hair, gynecomastia, and low work performance—as the main symptoms. Other sources have noted that low testosterone is also accompanied by changes in mood, with concomitant decreases in intellectual activity and cognitive function, as well as sleep disturbances, decreases in lean body mass, and increased fracture risk, he said.
Dr. Meuleman said the wide range of possible symptoms means that physicians must rely heavily on biochemical measurement of testosterone to diagnose the condition. A serum test assessing free bioavailable testosterone can be done clinically and should be carried out before 11 a.m. because of the circadian rhythm of testosterone levels in the blood. One-third of patients eventually diagnosed with low testosterone turn out to have classical causes such as Klinefelter's syndrome, which is undiagnosed in 75% of cases.
Studies looking at the effectiveness of replacing lost testosterone in men who have testosterone deficiencies have shown that testosterone supplementation can delay time to ischemia (Heart 2004;90:871–6). Supplementation also can improve distance in the shuttle walk test, boost mood in patients who are depressed, and improve lipid profiles while significantly decreasing total cholesterol, Dr. Meuleman added.
An ongoing study is looking at whether these findings can be extended to men with metabolic syndrome and type 2 diabetes. The randomized, double-blind, placebo controlled Effect of Transdermal Testosterone Replacement in Hypogonadal Men With Metabolic Syndrome or Type 2 Diabetes Mellitus (TIMES 2) study intends to test testosterone replacement to see if it reduces insulin resistance as measured by homeostatic model assessment (HOMA). Results from the study, which is being funded by ProStrakan Group Ltd., maker of a testosterone replacement gel, are expected to be reported in April 2009, Dr. Meuleman said.