Testosterone Replacement in Metabolic Syndrome and Inflammation

The features of Metabolic Syndrome (MetS) include abdominal obesity, atherogenic dyslipidemia, raised blood pressure, insulin resistance or glucose intolerance. These symptoms are also frequently found in hypogonadal men. Adipose tissue and androgens in male obesity are reciprocally linked. Total and free testosterone (T) are decreased in proportion to the degree of body fatness while T regulates insulin sensitivity and body composition. As a consequence, hypoandrogenism carries an additional independent risk for cardiovascular and metabolic disorders. Men with type 2 diabetes mellitus (T2D) exhibit lowered T levels that are inversely correlated to HbA1c. In addition, abdominal adiposity causes an impairment of testicular steroidogenesis that is directly linked to circulating adipokines; enhanced cytokine release from macrophage-infiltrated adipose tissue is pivotal to the pathogenesis of insulin resistance and atherosclerosis. Both MetS and T2D share with hypogonadism such a proinflammatory state. For this reason we performed a randomized controlled trial on the effects of TRT on insulin resistance and circulating inflammatory markers in a cohort of middle-aged men with mild hypogonadism and MetS at first diagnosis, that were not taking medications known to influence the investigated outcomes. We established strict criteria for enrollment and used a physiological replacing therapy. Given that testosterone replacement therapy (TRT) determines a reduction of body fat mass paralleled by an increase in fat free mass (6), and that TRT exerts an anti-inflammatory role inhibiting interleukins (IL), in particular the IL-6 gene (14), it remains to be established whether these independent effects also reflect in an improvement in insulin resistance.