Testosterone in men's health: a new role for an old hormone

Testosterone is an anabolic hormone with a wide range of beneficial effects on men's health. A considerable body of evidence suggests that testosterone (T) deficiency contributes to the onset and/or progression of type 2 diabetes mellitus (T2D), insulin resistance (IR), metabolic syndrome (MetS), cardiovascular disease (CVD), and erectile dysfunction (ED). Low testosterone precedes elevated fasting insulin, glucose, and hemoglobin A1c (HbA1C) values and may even predict the onset of diabetes. Low testosterone also produces adverse effects on cardiovascular health. Androgen deficiency is associated with increased levels of total cholesterol, low density lipoprotein (LDL), increased production of pro-inflammatory factors, increased thickness of the arterial wall, and contributes to endothelial dysfunction. Testosterone therapy of hypogonadal men improves insulin sensitivity, fasting glucose, and hemoglobin A1c levels. Testosterone supplementation restores arterial vaso-reactivity, reduces pro-inflammatory cytokines, total cholesterol, and triglyceride levels and improves endothelial function and high density lipoprotein (HDL) levels. The therapeutic role of testosterone in men's health, however, remains a hotly debated issue for a number of reasons, including the purported risk of prostate cancer. In view of the emerging evidence suggesting that androgen deficiency is a risk factor for MetS, T2D, IR, CVD, and ED, androgen replacement therapy in hypogonadal men may potentially reduce the risk for these pathologies.