These ‘modest’ changes are to blame for erectile dysfunction as you age, say doctors — it’s not testosterone

It’s not just your mind going soft.

Drops in testosterone have long been blamed for age-related declining erectile performance.

But a new study suggests something else may be at play.

“Although age and testosterone levels have long been considered an impetus for men’s declining sexual health, our research indicates that these changes more closely correlate with modest increases in blood sugar and other metabolic changes,” Dr. Michael Zitzmann, a professor and doctor of medicine at University Hospital in Muenster, Germany, said in a press release.

“This means that men can take steps to preserve or revive their reproductive health with lifestyle choices and appropriate medical interventions.”

The long-term study, which began in 2014 and wrapped in 2020, tracked 200 otherwise healthy men between the ages of 18 and 85.

By the end, 117 participants remained — all free of diabetes, heart disease or cancer — allowing researchers to isolate the effects of subtle metabolic changes on male reproductive health.

Despite aging, participants’ hormone levels and semen quality mostly remained in the normal range.

But one thing did take a noticeable hit: erectile function, particularly among those whose blood sugar levels crept up just slightly, but still fell well below the threshold for diabetes.

Interestingly, testosterone levels were not linked to erectile function, but they did correspond to the sex drives of participants.

Zitzmann hopes their findings — which were presented Saturday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, California — will help men take charge of their sexual health as they age.

“We’re hopeful that the information gleaned from this study will help doctors and their patients formulate effective male sexual health maintenance plans,” he said.

“We now know that it’s in our power to retain sexual and reproductive wellbeing in men, even as they age.”

The findings come amid public debate over testosterone replacement therapy (TRT), which has surged in popularity despite potential side effects.

A recent study found the male libido gets an astonishing boost from grape juice.

Meanwhile, experts say that — while sexual function unavoidably declines with age —men can improve their chances of staying reproductively healthy by avoiding smoking, excessive alcohol consumption and obesity.