Recent research presented at a major endocrinology conference in July 2025 has drawn attention to an emerging concern for men’s health: the impact of modestly elevated blood sugar levels on sexual performance. The findings indicate that even blood glucose levels falling below the diagnostic threshold for diabetes may contribute to a decline in erectile function and reduced libido in men, particularly those in middle age. These insights are prompting medical professionals to reconsider the importance of routine glucose monitoring even in men without a diabetes diagnosis.
The study, known as FAME 2.0, was conducted by researchers in Germany and tracked a group of 200 men ranging in age from 18 to 85 over a period of six years, from 2014 to 2020. The researchers intentionally selected participants without diabetes, cardiovascular disease, or cancer in order to isolate the effects of subtle metabolic shifts on reproductive and sexual health. By the end of the study, 117 men remained under observation. Their hormone levels, semen quality, erectile function, and glucose markers were all evaluated at regular intervals.
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While many hormonal measures remained within normal ranges across the group, the study revealed a striking connection between elevated HbA1c levels—a long-term indicator of blood sugar—and diminished sperm motility and erectile function. Importantly, these changes occurred even when HbA1c values were below the 6.5 percent threshold typically used to diagnose type 2 diabetes. Men with relatively modest increases in blood sugar were still at significantly higher risk of sexual health problems, a finding that challenges long-standing assumptions in clinical practice.
Interestingly, testosterone levels did not show a strong association with erectile dysfunction, although lower testosterone was linked to decreased libido based on survey responses. This suggests that while testosterone continues to play a role in sexual desire, it may not be the central factor in erectile capability for many men, especially those who are otherwise healthy. Instead, the data points to blood sugar as a more sensitive early indicator of trouble.
The lead researcher, Dr. Michael Zitzmann from University Hospital Münster, emphasized the clinical importance of these findings. He stated that men now have more tools than ever to monitor and manage their health, and that early attention to blood sugar can help preserve reproductive function. According to Dr. Zitzmann, the good news is that men can take proactive steps through diet, exercise, and medical care to protect their long-term sexual and reproductive health.
This research adds to a growing body of evidence suggesting that metabolic health and sexual function are closely intertwined. Traditionally, age and declining hormone levels have been cited as the primary culprits behind decreased sexual performance in men. However, this new study shifts the narrative toward metabolic indicators, especially blood glucose, as potentially more actionable and predictive metrics.
The implications go beyond sexual wellness. Chronic elevations in blood sugar, even those that do not meet criteria for diabetes, have been associated with early vascular changes, inflammation, and nerve damage. These underlying conditions are known to interfere with both cardiovascular and sexual health. Erectile dysfunction, in many cases, can serve as an early warning sign of broader circulatory or metabolic problems that may become more severe if left unchecked.
Given the findings, experts are urging healthcare providers to consider regular blood sugar testing as part of routine wellness screenings for men, particularly as they approach middle age. Lifestyle interventions—including weight management, physical activity, improved nutrition, and smoking cessation—are known to significantly improve insulin sensitivity and reduce the risks associated with elevated glucose. For many men, these changes could help stave off not only diabetes and heart disease but also preserve sexual function into later life.
This research is particularly relevant at a time when global rates of prediabetes are rising. According to the Centers for Disease Control and Prevention, more than one in three American adults has prediabetes, a condition marked by higher-than-normal blood sugar that has not yet reached diabetic levels. Most are unaware of their condition, which underscores the need for broader awareness and early testing.
Although the FAME 2.0 findings have not yet been peer-reviewed in a medical journal, they were presented at ENDO 2025, the annual meeting of the Endocrine Society, which is a leading forum for cutting-edge medical research. Experts caution that further studies are needed to establish the exact thresholds at which blood sugar begins to affect sexual health, and to evaluate how reversible these effects may be with targeted treatment.
Still, the message is becoming clear: even mild disturbances in glucose metabolism can have significant downstream consequences. For men, paying closer attention to blood sugar levels—even if they feel healthy—may prove to be a key step in maintaining not just sexual vitality, but overall health and quality of life as they age.
