Athletes who take growth hormone to boost their performance may be at risk for diabetes, British doctors warn.

Human growth hormone stimulates muscle growth and helps reduce body fat. It also allows athletes to recover faster from strenuous training.

Amateur athletes and bodybuilders can buy the hormone online, and unlike anabolic steroids, it is difficult to detect in screening tests.

In Monday's online issue of the British Journal of Sports Medicine, James Young and Aresh Anwar of University Hospital Coventry and Warwick in the U.K. report the case of the 36-year-old professional bodybuilder who admitted to using anabolic steroids for 15 years and artificial growth hormone for three years.

Symptoms reversed

The man was admitted for chest pain, and had lost 40 kilograms in 12 months. He also experienced excessive urination, thirst and appetite.

About one year after he started taking growth hormone, the man also took insulin, to counter the effects of high blood sugar. He stopped taking insulin after experiencing acute low blood sugar a few times at the gym.

Tests showed his liver was inflamed, his kidneys were enlarged, he had very high blood sugar and was dehydrated. He was diagnosed with diabetes.

Doctors gave the man intravenous fluids and gradually increasing amounts of insulin over five days. His symptoms cleared up and he was no longer diabetic, the study's authors said.

"We believe we have reported the first case of frank diabetes precipitated by supra-physiological recreational [growth hormone] abuse," they wrote.

Human growth hormone is produce by the pituitary gland and helps regulate growth during childhood, and metabolism in adults.

In January, a U.S. review of trials on elderly participants concluded that fountain of youth claims for the hormone are unfounded.

Side-effects include joint swelling and pain, carpal tunnel syndrome and a trend toward new diagnoses of diabetes or pre-diabetes.