GLP-1 Receptor Agonists May Improve Testosterone Levels and Sperm Quality in Men with Obesity, Studies Suggest
Key Insights
A meta-analysis of five randomized controlled trials found GLP-1 (search) medications have no negative impact on male hormones, sexual function, or sperm quality.
A 24-week semaglutide study showed improvements in sperm shape and cholesterol, while a 16-week liraglutide study demonstrated increased testosterone in men with obesity (search)-related low testosterone.
Researchers suggest GLP-1s may offer an alternative to testosterone replacement therapy, which can suppress sperm production, by treating the underlying cause of excess weight.
GLP-1 (search) receptor agonists, a class of medications widely prescribed for type 2 diabetes and weight loss, may improve testosterone levels and sperm quality in men with obesity (search), according to new research presented Monday at ENDO 2026, the Endocrine Society's annual meeting in Chicago, Illinois. The findings challenge concerns that these drugs could harm male fertility and instead suggest potential reproductive benefits.
Scientists at University Hospitals Coventry and Warwickshire (search) and Warwick Medical School (search) in Coventry, United Kingdom, conducted a systematic search of medical databases for published randomized controlled trials comparing GLP-1s to other treatments or placebo in men aged 18 to 65. Two independent reviewers assessed the studies to reduce bias, and five clinical trials ultimately met the eligibility criteria.
"These scientific reports showed that GLP-1s have no negative impact on hormones, sexual function or sperm quality," said endocrinologist and team lead Pratibha Natesh, M.B.B.S., M.R.C.P., M.Res., at Warwick Medical School (search).
Clinical Evidence Across Two Key Trials
Among the studies analyzed, a 24-week semaglutide trial revealed improvements in sperm shape and cholesterol levels while maintaining stable testosterone and hormone levels. In a separate 16-week liraglutide study focused on men with obesity (search) and low testosterone due to excess weight, participants experienced increases in testosterone and related hormones, with overall health outcomes surpassing those achieved with testosterone replacement alone.
"This work supports a shift away from prescribing testosterone replacement in men with obesity (search) and low testosterone and toward treating the underlying cause—excess weight and poor metabolic health—which can naturally restore hormone levels and preserve fertility," Natesh said.
Mechanisms and Clinical Implications
Natesh explained that weight loss associated with GLP-1 (search) use can promote healthier hormone function, including improved testosterone levels. Additionally, GLP-1 medications may reduce inflammation and metabolic stress, both of which can limit sperm production. If further studies confirm these findings, the drugs could provide a meaningful alternative to testosterone replacement therapy, which carries the risk of suppressing sperm production.
The clinical relevance is substantial: approximately 15% of couples in the United States experience difficulty conceiving, and more than half of those cases involve a male infertility (search) factor, according to Yale Medicine. Healthcare providers define infertility as not conceiving after 12 months of regular, unprotected sexual intercourse.
Limitations and Expert Caution
Despite the encouraging results, researchers and independent experts emphasized that the evidence base remains limited. Natesh stressed that the number of studies is small with varying results, and larger, better-designed studies are still needed to fully understand the effects on male fertility. She also noted that most of the reproductive benefits observed are likely indirect and that GLP-1s have not been evaluated as treatments for male infertility (search) or hypogonadism.
Dr. Lidia Mínguez Alarcón, a Spanish reproductive epidemiologist and assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School, who was not involved in the research, pointed out that the studies were only conducted on men with high body mass index, making it difficult to generalize the findings to the broader population.
Dr. Amin Herati, a urologist and director of male infertility (search) and men's health at Johns Hopkins Hospital, who was also not involved in the research, raised additional considerations. He noted that some individuals may struggle with weight loss due to underlying hormone problems, rather than hormone issues being a consequence of excess weight. "To know if it's the chicken or the egg," Herati stressed the importance of having a fertility evaluation with a reproductive urologist.
Herati also cautioned that not all weight loss benefits fertility. A sudden change in body fat, as observed with bariatric surgery and sometimes with GLP-1 (search) medications, may signal to the brain that it is not a safe time to reproduce, potentially limiting fertility. He recommends working with a doctor for guidance on healthy behaviors.
Broader Health Implications
Beyond fertility, good semen quality and healthy testosterone levels have been associated with better long-term health outcomes in men, Mínguez Alarcón noted. Natesh added that men who wish to conceive should keep their healthcare providers informed, as this may influence treatment decisions.
"Improving metabolic health can have positive effects far beyond weight alone," Natesh said. "By offering clear, evidence-based information about GLP-1 (search) weight loss and diabetes medications, we hope the research will help people make informed decisions about these drugs."