This food in excess can have a negative impact on men's sexual health.

Metabolic health issues, including small increases in blood sugar , are the primary drivers of change in older men's reproductive systems and sexual functioning , according to a study presented Saturday at ENDO 2025, the Endocrine Society's annual meeting in San Francisco, California.

"Although age and testosterone levels have long been considered a driver of decline in men's sexual health, our research indicates that these changes correlate more closely with modest increases in blood sugar and other metabolic changes," says Michael Zitzmann, professor and medical doctor at the University Hospital of Münster, Germany. "This means that men can take steps to preserve or revive their reproductive health with appropriate lifestyle choices and medical interventions," he adds.

These conclusions are drawn from a long-term study of healthy men (without diabetes mellitus, heart disease, and/or cancer) aged 18 to 85, which began in 2014 with 200 participants and concluded in 2020 with 117 participants. Researchers studied progressive changes in the participants' semen and hormonal profiles, erectile function, and metabolic health (BMI and blood sugar levels as measured by HbA1c testing).

The findings indicated that, over time, hormone levels and semen parameters largely remained within normal ranges. However, sperm movement and erectile function decreased in men with minimally elevated blood sugar levels who were below the diabetes threshold of 6.5% HbA1c. The study also found that while testosterone levels did not directly impact erectile function, they did correlate with participants' assessment of their libido.

"We hope the information gained from this study will help physicians and their patients develop effective plans for maintaining male sexual health. We now know that it is within our power to preserve men's sexual and reproductive well-being , even as they age," Zitzmann concludes.