Semaglutide doubled the percentage of normal sperm in obese men with type 2 diabetes and low testosterone, while testosterone replacement therapy significantly reduced sperm count.
2% → 4%Morphologically normal sperm doubled in the semaglutide group over 24 weeks (p=0.012), while testosterone therapy decreased sperm count
What the researchers found
Semaglutide significantly improved sperm morphology in obese men with type 2 diabetes and functional hypogonadism, while testosterone replacement therapy (TRT) significantly decreased sperm concentration and total count.
In the semaglutide group, morphologically normal sperm doubled from 2% to 4% (p=0.012). Compared to TRT, the semaglutide group had significantly higher normal sperm count, sperm concentration, and total sperm number after 24 weeks. Both treatments increased total testosterone and improved hypogonadism symptoms, but only TRT improved erectile function scores.
Why it matters
Men with obesity and type 2 diabetes frequently develop functional hypogonadism — low testosterone driven by excess weight rather than testicular failure. Testosterone replacement therapy is standard treatment but suppresses sperm production, creating a dilemma for men who want to preserve fertility. This study suggests semaglutide could address both the hypogonadism symptoms and fertility simultaneously — a significant advantage over TRT for men planning families.
The numbers in context
n=25 · 24 weeks · Semaglutide 1mg/week vs TRT 1000mg/10-12 weeks · Normal sperm: 2% → 4% (p=0.012) with semaglutide · Median age 50 · BMI 35.9 · Baseline sperm below 5th percentile
How the study worked
Twenty-five men with type 2 diabetes, obesity (median BMI 35.9), and functional hypogonadism were randomized to receive either semaglutide 1 mg/week subcutaneously or intramuscular testosterone undecanoate 1000 mg every 10-12 weeks for 24 weeks. Semen analysis and hypogonadism parameters were measured at baseline and 24 weeks. Erectile function and aging symptoms were assessed via validated questionnaires (IIEF-15 and AMS).
Who was studied
25 men with type 2 diabetes and obesity (median age 50, BMI 35.9) with functional hypogonadism
What this study cannot tell us
Small sample size of only 25 men limits statistical power and generalizability. The open-label design means neither participants nor investigators were blinded to treatment, introducing potential bias. The 24-week duration may not capture the full spermatogenesis cycle effects. Baseline sperm quality was very poor (below 5th percentile), so results may not apply to men with normal baseline fertility.
How to read the evidence
Moderate evidence from a randomized trial with a head-to-head comparison against standard therapy. The open-label design and small sample size (n=25) are limitations, but the findings are strengthened by objective semen analysis endpoints and statistical significance.
When this study was published
Published in 2025, this is a very recent study addressing an emerging question about GLP-1 agonists and male reproductive health — a topic with limited prior data.
The bigger picture
The GLP-1 agonist revolution has focused primarily on weight loss and blood sugar control, but this study adds male fertility to the growing list of potential benefits. As millions of men take semaglutide for obesity and diabetes, understanding its reproductive effects is critical. This trial suggests semaglutide may be especially valuable for the subset of obese, diabetic men who want to improve their testosterone levels without the fertility-suppressing effects of traditional hormone replacement.
Questions still open
- Would a longer treatment duration or higher semaglutide dose produce even greater improvements in sperm parameters?
- Does semaglutide's improvement in sperm morphology actually translate to improved fertility outcomes and conception rates?
- Would combining semaglutide with low-dose testosterone offer both fertility preservation and improved erectile function?
Common questions
Why does testosterone replacement therapy hurt sperm production?
How does semaglutide improve sperm quality if it's a diabetes drug?
Read the original research
Semaglutide improved sperm morphology in obese men with type 2 diabetes mellitus and functional hypogonadism.
Diabetes, obesity & metabolism, 27(2), 519-528
Citation
Gregorič, Nadan; Šikonja, Jaka; Janež, Andrej; Jensterle, Mojca. (2025). Semaglutide improved sperm morphology in obese men with type 2 diabetes mellitus and functional hypogonadism.. Diabetes, obesity & metabolism, 27(2), 519-528. https://doi.org/10.1111/dom.16042