A new wave of research is challenging long-held beliefs about men’s sexual well-being, revealing that even slightly elevated blood sugar levels—far below the traditional diabetes threshold—can quietly disrupt erectile function and sperm health. The findings, which stem from a six-year study recently presented at the Endocrine Society’s ENDO 2025 conference and published by sources including ScienceDaily and Neuroscience News, suggest lifestyle choices affecting blood sugar control play a far more significant role in men’s sexual vitality than previously recognised.
For men across Thailand, where rates of metabolic syndrome and prediabetes are surging, these new insights are a wake-up call. Historically, declining sexual health with age has been blamed on hormonal shifts, especially the drop in testosterone, or on the ageing process itself. But this robust study shifts the spotlight to the role of blood sugar—a facet closely tied to dietary, exercise, and sleep habits that are modifiable for many people, even before diabetes develops.
The extensive FAME 2.0 study tracked 200 healthy men aged 18 to 85 over six years, concluding with 117 participants who maintained regular follow-up. The cohort was carefully selected: none had diabetes, heart disease, or cancer, thus isolating the specific effects of subtle metabolic changes from overt chronic illnesses. Over the years, participants’ semen quality, hormonal profiles, erectile function, and key metabolic markers—especially the haemoglobin A1c (HbA1c) test—were assessed in depth.
As the research unfolded, a striking pattern emerged: average testosterone levels and overall semen parameters largely stayed within healthy limits, and age alone did not predict functional decline. Instead, sperm motility (the vital “swimming” ability of sperm) and erectile capacity waned most distinctly in men whose HbA1c values, an indicator of average blood sugar over several months, had crept up—but still sat below the formal diabetes diagnosis line of 6.5%. In other words, the seeds of trouble were sown long before classic diabetes symptoms would appear.
Professor of medicine and FAME 2.0 study leader at University Hospital in Muenster, Germany, summarised: “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. This means that men can take steps to preserve or revive their reproductive health with lifestyle choices and appropriate medical interventions.” (Neuroscience News)
Critically, the research also refined the role of testosterone. While this hormone did correlate with libido, or sexual desire, it did not significantly alter the physical ability to maintain an erection—pinpointing blood sugar as the bigger culprit for functional problems. These revelations have powerful implications for healthcare professionals. As the lead researcher shared, “We’re hopeful that the information gleaned from this study will help doctors and their patients formulate effective male sexual health maintenance plans. We now know that it’s in our power to retain sexual and reproductive well-being in men, even as they age.”
What does this mean for men in Thailand, where both sexual health and chronic disease remain sensitive, often under-discussed topics? According to the Ministry of Public Health, about 10.7% of Thais aged 15 or over exhibit markers of prediabetes—meaning their blood sugar is higher than normal but not yet high enough for a diabetes diagnosis (PLOS ONE). The prevalence is likely higher among men in urban areas like Bangkok, given changing diets and sedentary lifestyles. Medical experts routinely warn that prediabetes is a quiet epidemic, increasing the risks of heart disease and full-blown diabetes, but the new research adds another compelling reason to take it seriously—protecting sexual health and fertility.
Cultural context deepens the importance of these findings. In Thai society, issues of masculinity, virility, and fatherhood carry social weight. Traditionally, explaining sexual dysfunction might involve blaming stress, “wind” imbalances in traditional medicine, or simply “old age.” But scientific evidence now suggests that a chai yen yen (cool, moderate) approach to life—including regular physical activity, balanced food choices, and weight management—is not just helpful for physical health but crucial for maintaining sexual function and reproductive ability.
Notably, the FAME 2.0 study reinforces broader public health messaging about metabolic syndrome, a cluster of conditions including high blood pressure, abnormal cholesterol, and raised blood sugar that together drive chronic disease risk. According to research in the Journal of Metabolic and Diabetes in Healthcare, over one fifth (21.9%) of Thai adults have metabolic syndrome, mirroring global patterns (Dove Medical Press).
Behind the cutting-edge science is a practical action plan: Men do not need to wait for severe symptoms or a diabetes diagnosis to address blood sugar. The researchers underscore manageable interventions—regular medical check-ups, HbA1c screening, increased physical activity (even 30 minutes a day can make a difference), reducing sugary foods and processed carbohydrates, and avoiding excess alcohol. For those already showing signs of prediabetes, targeted support from healthcare professionals is crucial.
Medical professionals in Thailand echo these recommendations. Endocrinologists affiliated with Thailand’s leading teaching hospitals advocate for routine metabolic health checks in primary care, particularly for middle-aged men reluctant to talk about sexual health concerns. Urologists at major Bangkok hospitals report rising cases of erectile difficulty linked to early-stage metabolic changes, saying early lifestyle modification yields not only better sexual health outcomes but also protects the heart, kidneys, and brain.
Sexual health educators and family planning counsellors point out that public messaging in Thailand still largely focuses on sexual safety and STI prevention, while the new research calls for integrating metabolic health into men’s sexual wellness campaigns. Adapting messaging to reduce huap (shame) and promote positive, preventive conversations can empower more men to seek early help.
Alongside the medical analysis, historical context matters. Thai medical tradition, as reflected in royal chronicles and temple inscriptions, has long linked health of the “vital essence” (prana, or lom) to diet and lifestyle, echoing modern findings that blood sugar imbalances sap both energy and virility. Today, integrating biomedical and holistic approaches can help address stigmas and support collective well-being.
Looking ahead, the FAME 2.0 study is already spurring further research into specific blood sugar thresholds that predict functional decline, with clinical trials underway for Thai men at risk for metabolic syndrome. Policy experts are urging the Ministry of Public Health to strengthen community-based screenings for high-risk groups, while digital health startups in Bangkok are launching mobile apps to help men monitor their diets, blood sugar, and sexual health anonymously.
For Thai readers, the take-home message is clear: safeguarding sexual and reproductive wellness begins not with expensive medications or secret remedies, but with everyday habits around food, movement, stress management, and routine health checks. Early awareness and intervention can maintain both khwam pen phuchai (manliness or masculinity) and overall quality of life, well into old age.
Practical recommendations for Thai men and their families: Schedule annual check-ups with blood sugar screening (including the HbA1c test), cultivate a physically active lifestyle—consider joining a local football team or walking around your neighbourhood park—cut back on sugary drinks and snacks, prioritise home-cooked meals with fresh ingredients, and seek confidential advice from health professionals if experiencing changes in sexual health. For community leaders, employers, and health educators, now is a crucial moment to destigmatise conversations around men’s wellness, building healthier and happier futures for all.
For more details on the research, see ScienceDaily and Neuroscience News. For background on Thailand’s prediabetes rates: PLOS ONE, and for further context on metabolic syndrome: Dove Medical Press.