Data presented at ENDO 2025 in San Francisco, California suggest that metabolic health factors may be the primary driver of changes in sexual function among healthy aging men.1
Increases in HbA1c were shown to have a greater influence on sexual wellbeing than age alone.
Specifically, the investigators found that in healthy aging men without developing diabetes mellitus, modest increases in HbA1c were linked with declines in sperm motility and erectile function. This increase in HbA1c was shown to have a greater influence on sexual wellbeing than age alone.
“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,” explained lead author Michael Zitzmann, MD, PhD, professor and doctor of medicine at University Hospital in Muenster, Germany, in a news release on the findings.2 “This means that men can take steps to preserve or revive their reproductive health with lifestyle choices and appropriate medical interventions.”
Data for the study were collected as part of the longitudinal FAMe 2.0 study, which began in 2014. The trial recruited 200 healthy patients (no history of cancer, cardiovascular events, or diabetes mellitus) aged 18 to 85 years at baseline. In 2020, 117 patients returned for follow-up. For the study, participants completed assessments on the Erectile Function domain of the International Index of Erectile Function (IIEF-EF) questionnaire as well as the Aging Male Symptoms (AMS) score.
Results showed that, over time, hormone levels and semen parameters (volume, total sperm count, concentration, vitality) remained within the normal range with no significant decline. However, decreases in serum concentration of total and free testosterone were observed in patients who experienced increases in BMI (P = .004 and P = .002, respectively) or HbA1c (P = .003 and P = .001, respectively). Further, declines in progressive sperm motility were associated with age, with significant declines observed in patients over the age of 65 years (P = .002). This decline was associated with increases in HbA1c (P = .008; all total values remained below the 6.5% HbA1c diabetes threshold).
Data also showed that erectile function declined in men over the age of 45 years (P = .001), but only in those who experienced increases in HbA1c (P = .002). Erectile function was not associated with changes in total (P = .52) or free testosterone (P = .47).
However, decreasing levels of total (P = .04) or free testosterone (P = .003) were significantly associated with worse AMS scores, specifically in the sexual subdomain (loss of libido). According to the authors, this association was correlated with increasing HbA1c levels (P = .002) but not aging (P = .57).
The authors noted, “Healthy men without deterioration of the metabolic state experience minimal declines in fertility, sexual wellbeing, and sex hormone levels with age.”
Overall, these findings suggest that sexual functioning in healthy aging men could be preserved with adequate lifestyle choices.
“We’re hopeful that the information gleaned from this study will help doctors and their patients formulate effective male sexual health maintenance plans,” Zitzmann concluded in the news release.2 “We now know that it’s in our power to retain sexual and reproductive wellbeing in men, even as they age.”
REFERENCES
1. Zitzmann M, Krallmann C, Cremers J, Kliesch S, Bier S. Healthy ageing men experience decline of sexual function and fertility dependent on increases of HbA1c within the normal range: the longitudinal FAMe 2.0 study. Presented at: ENDO 2025. July 12-15, 2025. San Francisco, California. Abstract SAT-169. https://www.newswise.com/pdf_docs/175157430185708_Zitzmann%20Abstract.pdf
2. High blood sugar may have a negative impact on men’s sexual health. News release. Endocrine Society. July 8, 2025. Accessed July 14, 2025. https://www.newswise.com/articles/high-blood-sugar-may-have-a-negative-impact-on-men-s-sexual-health/?sc=mwhr&xy=10016681