High blood sugar may have a negative impact on men's sexual health

Metabolic health factors, including small increases in blood sugar, are the main drivers of change in the reproductive systems and sexual functioning of aging men, according to a study being presented Saturday at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, Calif.

“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,” said Michael Zitzmann, M.D., Ph.D., professor and doctor of medicine at University Hospital in Muenster, Germany. “This means that men can take steps to preserve or revive their reproductive health with lifestyle choices and appropriate medical interventions.”

These conclusions follow a long-term study of healthy men (without diabetes mellitus, heart disease and/or cancer) aged 18-85 that began in 2014 with 200 participants and concluded in 2020 with 117 participants. Researchers studied progressive changes in participants’ semen and hormonal profiles, erectile functioning and metabolic health (BMI and blood sugar levels marked by the HbA1c test).

Findings indicated that over time hormone levels and semen parameters stayed largely within normal ranges. However, sperm movement and erectile function declined in men with minimally elevated blood sugar levels that were below the 6.5% HbA1c diabetes threshold. The study also found that while testosterone levels did not have a direct impact on erectile function, they did correlate with participants’ libido assessment.

“We’re hopeful that the information gleaned from this study will help doctors and their patients formulate effective male sexual health maintenance plans,” Zitzmann added. “We now know that it’s in our power to retain sexual and reproductive wellbeing in men, even as they age.”

This research was conducted as part of the FAME 2.0 study.

About the Endocrine Society
Endocrinologists are at the core of solving the most pressing health problems of our time, including diabetes, obesity, infertility, bone health, and hormone-related cancers. The Endocrine Society is the largest global organization of scientists devoted to hormone research and physicians who care for people with hormone-related conditions.

With more than 18,000 members in 133 countries, the Society serves as the voice of the endocrine field. Through its renowned journals and ENDO, the world's largest endocrine meeting, the Society accelerates hormone research, advances clinical excellence in endocrinology, and advocates for evidence-based policies on behalf of the global endocrine community. To learn more, visit our online newsroom.