Research has uncovered some surprising effects of treatments that manipulate the male sex hormone testosterone. Specifically, testosterone seems to affect metabolism—the body’s energy-related chemical processes. For example, men with prostate cancer who are prescribed drugs that block testosterone production develop type 2 diabetes, cardiovascular disease, and other problems related to metabolism at higher rates than other men.
To examine this link directly, researchers supported by the Contraceptive Discovery and Development Branch tested the metabolic effects of testosterone manipulation in young, healthy men. They measured a number of factors, such as blood levels of other hormones, that might help explain what was going on.
The researchers found that men who were given a drug to block their testosterone production were releasing more insulin, which signaled cells to take in sugar. (Rising blood levels of insulin precede type 2 diabetes.) Levels of two other metabolism-controlling hormones also rose while the men were taking the testosterone-blocking drug. In contrast, men who received the testosterone-blocking drugs along with supplemental testosterone did not have any changes in their metabolic hormones.
The results of the research support the hypothesis that testosterone acts on metabolism directly, rather than through secondary effects on body weight. Although this study was relatively small, it has important implications for understanding the potentially serious metabolic side effects of treatments that affect testosterone, such as testosterone-blocking cancer treatments or, potentially, testosterone-based male contraception (PMID: 21797916).