Testosterone (C₁₉H₂₈O₂) belongs to a class of steroid hormones called androgen and is found in mammals, reptiles, birds, and other vertebrates. In mammals, Testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.

In men, Testosterone plays a critical role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle, bone mass, and the growth of body hair. In the absence of Testosterone stimulation, spermatogenesis does not proceed beyond the meiosis stage.

In addition, Testosterone is essential for health and well-being as well as the prevention of osteoporosis. On average, an adult human male body produces about ten times more Testosterone than an adult human female body, however, females are more sensitive to the hormone. Testosterone plays a significant role in glucose homeostasis and lipid metabolism. A number of studies have shown an inverse relationship between the plasma Testosterone and severity of the metabolic syndrome, which is a clustering of risk factors predisposing to type 2 diabetes (T2D), atherosclerosis and cardiovascular diseases.