A new study from the Tulane University School of Medicine has discovered that testosterone actually acts as an anti-diabetic hormone in men, and this knowledge may help identify new treatment options for type 2 diabetes. It has long been known that low testosterone levels increase the risk of type 2 diabetes, but this is the first time the cause has been identified.
Testosterone helps men regulate their blood sugar levels by triggering key signaling mechanisms in the clusters of cells located in the pancreas, known as islets, that produce insulin. Men with decreased testosterone due to age or prostate cancer therapies are at higher risk for the disease.
The study used male mice that were specially bred to have pancreatic beta cells that lacked the receptor to testosterone, known as the androgen receptor. The mice were fed a diet rich in sugars and fats and then tested for their response to glucose. The mice with no androgen receptors all showed lower secretion of insulin, which led to glucose intolerance when compared with normal mice in the control group.
When the researchers administered glucose and testosterone directly to human islet cells that had been treated with an androgen receptor inhibitor, and islet cells from mice that had no androgen receptors, both showed decreased insulin production when compared to islet cells with normal testosterone receptors.
Further experiments with mouse and human islet cells showed that the insulin-producing effect of testosterone could be stopped by inhibiting the hormone the body produces after a meal. The research team suggests that testosterone amplifies the islet impact of this hormone, which is presently used as a treatment for diabetes.