Long-term use of GLP-1 has no negative effects on male hormones or fertility, according to research to be presented Monday at the Endocrine Society’s annual meeting ENDO 2026 in Chicago, Illinois. In fact, the research team found that GLP-1 may improve testosterone levels and sperm quality in men with obesity-related low testosterone, while also addressing the underlying effects of obesity.
Scientists from Coventry and Warwickshire University Hospitals and Warwick Medical School in Coventry, UK, made the discovery after searching medical databases of published randomized controlled trials. They focused on studies that compared GLP-1 with other treatments and placebos in men aged 18 to 65. The researchers primarily looked at changes in testosterone and other hormones that control testicular function, but they also looked at sperm quality, weight, blood sugar, cholesterol, and overall metabolic health. Two independent reviewers checked the studies to reduce bias, and five clinical trials met the eligibility criteria.
These scientific reports showed that GLP-1 has no negative effects on hormones, sexual function, or sperm quality. For example, a 24-week study of semaglutide revealed improved sperm shape and cholesterol levels while keeping testosterone and hormone levels stable. A 16-week study of liraglutide in men with low testosterone due to obesity and excess weight demonstrated that men experienced an increase in testosterone and related hormones. Their overall health outcomes were better than with testosterone supplementation alone.
This research supports a shift from prescribing testosterone supplementation for obese and low-testosterone men to treating the underlying causes of excess weight and decreased metabolism, which can naturally restore hormone levels and maintain fertility. ”
Pratibha Natesh, MBBS, MRCP, M.Res., Endocrinologist, Team Leader, Warwick Medical School
Although the health outcomes of these clinical trials are positive, Natesh stressed that the number of studies is small and results are mixed, so larger and better-designed studies are still needed to fully understand the impact on male fertility. Additionally, physicians should keep in mind that most of the observed reproductive benefits are likely indirect and that GLP-1 has not been evaluated as a treatment for male infertility or hypogonadism.
Nevertheless, by providing clear evidence-based information about GLP-1 weight loss and diabetes drugs, Dr. Natesh hopes this study will help people make informed decisions about these drugs.
“Improving metabolic health has positive effects far beyond just weight,” she said.
