Background: While metabolic disorders are well-established contributors to testosterone decline and erectile dysfunction (ED), little is known about the natural progression of reproductive parameters in healthy aging men.
Objectives: This study aimed to evaluate longitudinal changes in reproductive parameters and sought to determine the influence of body mass index (BMI) and glycated hemoglobin (HbA1c) on these changes.
Patients and methods: A total of 197 healthy men (aged 18-84 years) were assessed at baseline (FAMe 1), with 117 participants returning for follow-up (FAMe 2) after approximately 6 years. All participants underwent a thorough andrological examination.
Results: Total and free testosterone levels declined significantly over 6 years in men older than 25 years at baseline (p < 0.05). FSH levels increased significantly in men older than 35 years at FAMe 1 (p < 0.05), while LH and SHBG remained unchanged. Despite moderate declines, semen parameters remained mostly within physiological limits. Erectile function exhibited a moderate but progressive decline (p < 0.001). In men over 45 years, neither age (p = 0.13) nor testosterone (p = 0.52) influenced erectile function, while an increment of HbA1c levels was significantly associated with deteriorating erectile function (p = 0.002). Similarly, AMS scores significantly increased after age 45, which was strongly correlated with higher HbA1c levels (p = 0.001).
Discussion: While testosterone levels declined with aging, they remained within the normal range, suggesting that healthy men experience only apparently mild reproductive aging. Erectile function and hypogonadism-like symptoms were more strongly associated with glycemic control than with testosterone levels.
Conclusion: In healthy men, reproductive and sexual aging occur gradually, with testosterone and semen parameters largely preserved over time. However, metabolic health, rather than testosterone, plays a key role in the progression of ED and hypogonadism-like symptoms, emphasizing the need for preventive metabolic interventions to maintain reproductive health.
Keywords: erectile function; hypogonadism; male reproductive aging; metabolic health; semen parameters; testosterone decline.
© 2025 The Author(s). Andrology published by John Wiley & Sons Ltd on behalf of American Society of Andrology and European Academy of Andrology.