In the study, funded in part by drug maker Novo Nordisc, researchers looked the causes of death in almost 2,000 German men aged 20 to 79 years. The men with low testosterone at the start of study, which had an average follow up period of 7 years, had a more than 2.5 times greater risk of dying during the next 10 years compared with men with higher testosterone. These men tended to be older, fatter and had a greater prevalence of diabetes and high blood pressure than the men with higher testosterone levels, Haring said.

This difference was not explained by age, smoking, alcohol intake, level of physical activity or increased waist circumference (a risk factor for diabetes and heart disease), according to researcher author Robin Haring, a Ph.D. student from Ernst-Moritz-Arndt University of Greifswald, Institute for Community Medicine.

Low testosterone levels predicted increased risk of death from cardiovascular disease and cancer but not death of any other single cause, the study found.