GLP-1 Medications Show No Harm to Fertility – and May Benefit Men With Obesity, New Analysis Finds

Key Takeaways: 

• A new review of randomised controlled trials found that GLP-1 medications do not harm male hormones, sexual function or sperm quality after long-term use, and in some cases appear to improve them.
  
• In men with obesity and weight-related low testosterone, treating the underlying excess weight and poor metabolic health may naturally restore hormone levels while preserving fertility – potentially offering an alternative to testosterone replacement therapy.
  
• The findings are encouraging but preliminary; with only five eligible trials and varying results, the research team stresses that larger, better-designed studies are still required.
  
  
  

A reassuring picture for male reproductive health

Long-term use of GLP-1 medications does not harm male hormones or fertility, according to research being presented on Monday at ENDO 2026, the Endocrine Society’s annual meeting in Chicago, Illinois. The findings go further still: the research team reported that GLP-1 medications may actually raise testosterone levels and improve sperm quality in men who have obesity-related low testosterone, while simultaneously tackling the metabolic problems that sit beneath those hormonal changes.

How the study was carried out

The work was led by scientists at University Hospitals Coventry and Warwickshire and Warwick Medical School in Coventry, United Kingdom. The team searched medical databases for published randomised controlled trials, narrowing their focus to studies that compared GLP-1 medications against other treatments or a placebo in men aged 18 to 65.

Their primary interest lay in changes to testosterone and the other hormones that govern testicular function. Alongside this, they also assessed sperm quality, body weight, blood sugar, cholesterol and broader markers of metabolic health. To reduce the risk of bias, two independent reviewers checked each study, and five clinical trials ultimately met the eligibility criteria.

What the trials revealed

Across these reports, GLP-1 medications showed no negative effect on hormones, sexual function or sperm quality.

In one 24-week semaglutide study, men saw improvements in sperm shape and cholesterol levels, while their testosterone and other hormone levels remained stable. A separate 16-week liraglutide study, conducted in men with obesity and low testosterone driven by excess weight, found that participants experienced increases in testosterone and related hormones. Notably, their overall health outcomes were better than those achieved with testosterone replacement alone.

Treating the cause rather than the symptom

For the research team, the most significant implication concerns how clinicians approach low testosterone in men with obesity.

“This work supports a shift away from prescribing testosterone replacement in men with obesity and low testosterone and toward treating the underlying cause – excess weight and poor metabolic health – which can naturally restore hormone levels and preserve fertility,” said endocrinologist and team lead Pratibha Natesh, M.B.B.S., M.R.C.P., M.Res., at Warwick Medical School.

Important caveats

While the outcomes are positive, Dr Natesh was careful to temper expectations. The body of evidence remains small and the results vary between studies, so larger and better-designed trials are needed before the effects on male fertility can be fully understood.

She also cautioned that most of the reproductive benefits observed are likely to be indirect, flowing from improved metabolic health rather than from any direct action on the reproductive system. Importantly, GLP-1 medications have not been evaluated as treatments for male infertility or hypogonadism, and should not be regarded as such.

The wider takeaway

By providing clear, evidence-based information about GLP-1 weight-loss and diabetes medications, Dr Natesh hopes the research will help people make better-informed decisions about these treatments.

“Improving metabolic health can have positive effects far beyond weight alone,” she said.

Source: Endocrine Society