Can Small Changes in Blood Sugar Impact Men's Reproductive Health? Study Sheds Light

A long-term study presented at ENDO 2025, the Endocrine Society's annual meeting in San Francisco, has found that modest increases in blood sugar and other metabolic health factors are more closely linked to changes in sexual and reproductive function in aging men than age or testosterone levels alone.

The study challenges traditional views that primarily attribute male sexual decline to aging or falling testosterone. Instead, researchers point to the role of subtle metabolic changes particularly rising blood sugar as key contributors to declining sperm mobility and erectile function in otherwise healthy men.

The study began in 2014 and followed 200 healthy men aged 18 to 85 who did not have diabetes, cardiovascular disease, or cancer. By 2020, 117 participants remained. Over the course of the study, researchers regularly assessed semen quality, hormone levels, erectile functioning, and key metabolic indicators such as body mass index and HbA1c, a marker for blood sugar levels.

The results revealed that while hormone levels and semen parameters generally remained within normal ranges, sperm motility and erectile function declined in men with slightly elevated HbA1c levels even when those levels were still below the diabetes threshold of 6.5%. Interestingly, testosterone did not directly impact erectile function, though it was associated with libido.

"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."

"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 well-being in men, even as they age."

The findings offer a promising direction for men seeking to maintain sexual health through better metabolic control and lifestyle changes, rather than relying solely on hormone therapy or aging-related assumptions.

Reference: https://www.endocrine.org/