A long-term study of healthy men shows that even non-diabetic glucose levels can slow sperm, weaken erections, and reduce libido. The findings suggest that controlling blood sugar — not just hormone levels — could be key to preserving sexual and reproductive health in aging men.
Blood Sugar Drives Male Reproductive Changes
Changes in reproductive and sexual health among aging men are more strongly linked to metabolic factors, especially slight rises in blood sugar, than to age alone, according to findings shared at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco, California.
“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.”
