A groundbreaking new study has challenged decades-old assumptions about men’s sexual health, showing that even slightly elevated blood sugar—well below diabetic levels—can significantly impair sexual function and sperm mobility. The findings, which upend the notion that age or testosterone alone drive male sexual decline, have special implications for Thai men amid rising rates of metabolic disorder and changing lifestyles nationwide.
For years, it was widely believed that reduced libido, erectile challenges, and compromised sperm quality in men naturally came with aging or declining testosterone. However, the international team led by physicians at University Hospital in Münster, Germany, has demonstrated that subtle metabolic changes—marked primarily by the HbA1c blood sugar test—correlate far more closely with sexual health decline than either age or testosterone levelsScience Daily. The study, known as FAME 2.0, followed nearly 200 healthy men aged 18-85 in a rigorous six-year analysis ending in 2020, excluding any participants with diabetes, heart disease, or cancer to isolate the effects of modest (pre-diabetic) blood sugar elevation.
The significance is considerable for the Thai public, where the prevalence of high blood sugar and prediabetes has soared in the past two decades. According to the Ministry of Public Health, nearly one in three Thai adults now falls within the prediabetic range, a trend fueled by sedentary lifestyles, urbanization, and a growing appetite for energy-dense processed foods. With diabetes-related complications already costing the Thai health system tens of billions of baht annually, this new research suggests sexual and reproductive health burdens may be an unrecognized consequence for countless men.
Key findings from the FAME 2.0 study reveal that, while hormone and overall semen levels stay within normal ranges over time, men with minimally increased blood sugar (still under the 6.5% diagnostic threshold for diabetes) showed marked declines in sperm motility and erectile function. Professor Zitzmann, the study’s lead, explains, “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”Science Daily.
Supporting evidence was presented at the ENDO 2025 meeting, where endocrinologists stressed that blood sugar, not age, is the “strongest driver” of sexual function decline in aging malesEndocrine.org.Neuroscience News. Crucially, the study confirmed that testosterone influenced sexual desire but did not directly impact erectile performance—a nuance that challenges some current clinical practices in Thailand, where testosterone therapy remains popular among middle-aged men worried about virility.
Thai experts in men’s health at leading Bangkok hospitals have begun to take note. A reproductive medicine specialist at a government hospital told the Bangkok Post: “This is a wake-up call for Thai men. We have been underestimating the impact of minor blood sugar elevations, especially among those who do not consider themselves at risk for diabetes. This clarifies why some men, even in their forties and fifties and with normal testosterone, experience erectile issues or declining fertility despite overall good health.”
The implications are wide-ranging across Thailand, a country where family-building and sexual vitality are culturally valued and often tied to masculinity and social status. In traditional contexts, declining sexual function was often linked to “khwan” (life energy) loss or simply attributed to inevitable old age. However, the new data suggest that dietary and lifestyle changes since the 1980s—such as a shift from traditional rice and fresh foods toward sweetened beverages, processed snacks, and more sedentary jobs—may be having a direct, measurable effect on men’s reproductive health. A large-scale study from Mahidol University recently showed that Thai men’s average daily sugar intake now exceeds World Health Organization recommendations, underscoring the urgency of these metabolic findings.
International evidence bolsters the link found by the FAME 2.0 team. A recent review in The Journal of Sexual Medicine found that men with prediabetic blood sugar profiles are up to 40% more likely to report erectile dysfunction than their peers with normal glucose levels—a risk only partially mitigated by age or testosteronePubMed. Moreover, the relationship between glucose metabolism and sperm health points to broader issues with oxidative stress and inflammation, both known to disrupt the delicate hormonal balance needed for reproductive function.
To control for other variables, the German research team tracked BMI (body mass index), lifestyle factors, and hormone panels. Their data show that lifestyle-driven blood sugar increases can harm sperm motility even before traditional diabetes develops, aligning with concerns rapidly growing in Thai reproductive clinics, where unexplained male infertility is on the rise.
What does this mean for Thai households and healthcare providers? First, standard sexual health assessments for men should incorporate metabolic testing, particularly of HbA1c, long before diabetes is diagnosed. Second, interventions need to shift from testosterone supplementation and symptomatic treatments toward early lifestyle-based prevention–especially in at-risk groups such as those with sedentary jobs, high processed sugar consumption, or a family history of metabolic syndrome.
Experts at Chulalongkorn University recommend a national campaign focusing on men’s metabolic health as a pillar of reproductive and family well-being, not just as a strategy to reduce diabetesBangkok Post. A public health policy analyst at a government ministry summarized: “Sexual health in men is more than just testosterone. The real threat for our modern society is unchecked increases in blood sugar, which can easily go undetected for years. Primary care clinics in Thailand should screen more rigorously and offer practical advice on diet and exercise to younger adult men, not just those at obvious cardiovascular risk.”
The cultural dimension should not be overlooked. Sexual vitality among Thai men is often closely linked with self-esteem, intimate relationships, and family planning decisions. In some communities, men may feel embarrassed or reluctant to seek help for erectile or fertility concerns. The new research provides a scientific foundation to reframe these issues as metabolic, rather than purely age or masculinity-related. Health campaigns could leverage respected community figures, including Buddhist monks, to promote healthy eating and active lifestyles, capitalizing on the strong social networks already present in many provinces.
The momentum behind these findings has global echoes. Similar warnings are emerging in the US and Europe, where men in their thirties and forties are showing declining sperm parameters and rising rates of erectile dysfunction linked to “metabolic inflexibility”—the body’s reduced ability to manage blood sugar surgesNeuroscience News. In Asia, where diabetes rates have skyrocketed, the implications for national fertility trends and social stability are profound. Thailand’s own fertility rate has fallen below replacement level, a trend previously blamed chiefly on urbanization and delayed marriage, but potentially compounded by understated male-factor contributions.
Looking to the future, digital health technologies could play a vital role in early metabolic monitoring for Thai men, empowering individuals to track changes in blood sugar and receive targeted advice well before complications set in. Already, several Bangkok hospitals offer online platforms and mobile apps for health screening, which could be expanded to focus specifically on men’s sexual and metabolic health.
In summary, the main actionable takeaway for Thai readers is clear: men of all ages—especially those in midlife—should ask for routine blood sugar and HbA1c checks as part of their annual health assessment. Practicing the “three S” formula widely promoted by Thai health authorities: sensible eating, sufficient exercise, and stress management, can make a tangible difference not only in diabetes prevention but also in maintaining sexual and reproductive vitality. For those already experiencing symptoms, early consultation with a urologist or endocrinologist—rather than turning to over-the-counter tonics or unproven herbal remedies—can lead to targeted, effective solutions tailored to metabolic risk profiles.
For further reading on related local campaigns and expert advice, visit the Ministry of Public Health’s chronic disease prevention portal, or explore more on the metabolic underpinnings of male sexual health at publications from international research societies.