As men grow older, many expect changes in their sexual and reproductive health.
While these changes have often been blamed on age and dropping testosterone levels, new research suggests that even small increases in blood sugar might play a bigger role than previously thought.
This research comes from a long-term study presented at ENDO 2025, the Endocrine Society’s annual meeting in San Francisco. The study was led by Dr. Michael Zitzmann from the University Hospital in Muenster, Germany.
According to Dr. Zitzmann, “Although age and testosterone levels have long been considered a main reason for men’s declining sexual health, our research shows these changes are more closely tied to slight increases in blood sugar and other metabolic factors.”
This means that men may be able to keep their reproductive health stronger for longer through healthy habits and medical care that manage their blood sugar and overall metabolic health.
The study followed healthy men between the ages of 18 and 85 who did not have diabetes, heart disease, or cancer. The research began in 2014 with 200 men and ended in 2020 with 117 participants.
Over six years, the team looked at the men’s sperm quality, hormone levels, erectile function, body weight, and blood sugar, which was measured using the HbA1c test.
One surprising result was that most hormone levels and sperm measures stayed in the normal range throughout the study. However, there was a noticeable decline in sperm movement and erectile function in men who had slightly elevated blood sugar levels.
These levels were still below the official diabetes mark of 6.5%, showing that even small increases in blood sugar might affect sexual health.
Another finding was that testosterone levels didn’t directly affect the ability to get or maintain an erection. Instead, testosterone was more linked to how strong a man’s sex drive, or libido, was.
This study is part of a project called FAME 2.0 and gives doctors helpful information to support their male patients. Dr. Zitzmann hopes this research will help healthcare providers and men build effective plans to maintain sexual and reproductive health as they age.
“We now know that it’s possible to hold on to sexual and reproductive well-being, even as we grow older,” he said.
Overall, this study suggests that focusing on good blood sugar control—through diet, exercise, and possibly medication—could be key for men who want to stay healthy in both body and sexual function. It also encourages men to pay attention to their metabolic health before serious problems like diabetes develop.
For more health information, please see recent studies about bone drug that could lower risk of type 2 diabetes, and results showing eating more eggs linked to higher risk of type 2 diabetes.
For more about diabetes, please read studies about This drug combo can treat type 2 diabetes in the long run effectively and findings of Eating fewer than 3 meals a day may help reduce risk of type 2 diabetes and obesity.
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