Recent randomized trial data summarized by researchers at University Hospitals Coventry and Warwickshire and Warwick Medical School suggest that GLP-1s may have beneficial effects on reproductive and metabolic outcomes in men with obesity. The review, presented in an ENDO 2026 research video by Pratibha Natesh, MBBS, MRCP, MRes, examined whether GLP-1 receptor agonists influence testosterone, other hormones that regulate testicular function, and sperm quality, alongside standard metabolic endpoints.
The investigators conducted a systematic search of medical databases for published randomized controlled trials that compared GLP-1 receptor agonists with placebo or other treatments in men aged 18–65. Two independent reviewers screened studies to limit bias. The review ultimately included five randomized clinical trials that met the eligibility criteria.
Across the included trials, investigators collected data on reproductive hormones (including testosterone), sperm parameters, body weight, glycemic measures, cholesterol, and wider measures of metabolic health. The review specifically focused on disentangling whether any observed reproductive benefits were secondary to weight loss and improved metabolic status or whether GLP-1 analogs might exert a direct effect on the reproductive axis.
The pooled evidence from the five trials indicated no harmful effects of GLP-1 therapies on reproductive hormones, sexual function, or sperm quality. Two trial examples highlighted in the report illustrate observed benefits:
A 24-week trial of semaglutide reported improvements in sperm morphology and reductions in cholesterol while maintaining stable testosterone and related hormone levels.
A 16-week trial of liraglutide in men with obesity and low testosterone showed increases in testosterone and other hormones involved in testicular function. In that study, participants treated with liraglutide achieved better overall health outcomes than men receiving testosterone replacement alone.
Taken together, these findings suggest that GLP-1 receptor agonists can be associated with improved metabolic markers and some measures of sperm quality, and in some contexts may coincide with increases in circulating testosterone in men whose hypogonadism appears related to excess weight.
Based on the available trial reports, the review authors—led by Pratibha Natesh—propose that clinicians consider prioritizing treatment of the underlying drivers of obesity-related hypogonadism, namely excess weight and poor metabolic health, rather than reflexively prescribing testosterone replacement. Addressing weight and metabolic dysfunction with interventions that include GLP-1 receptor agonists may restore endogenous hormone levels and help preserve fertility.
The authors argue this approach could reduce unnecessary testosterone replacement in men whose low testosterone is secondary to obesity and metabolic disease, because improving metabolic health may normalize the reproductive hormone milieu.
The investigators caution that the evidence base is limited. Only five randomized trials met inclusion criteria, and the studies varied in design, duration and measured outcomes. The review explicitly notes that most reproductive benefits observed are likely indirect and mediated by weight loss and metabolic improvement rather than confirmed direct actions of GLP-1s on the hypothalamic–pituitary–testicular axis.
The authors emphasize the need for larger, rigorously designed randomized trials to define the magnitude and durability of reproductive benefits, to determine whether GLP-1s have direct effects on reproductive physiology, and to assess long-term effects on fertility and hypogonadism outcomes. They also note that GLP-1s have not been evaluated as therapies for male infertility or primary hypogonadism.
Clinicians should discuss the current evidence with patients considering GLP-1 therapy for weight loss or diabetes, particularly men concerned about fertility or low testosterone. Key points for clinical counseling based on the review include:
Inform patients that randomized trials to date have not demonstrated harm to hormones, sexual function or sperm quality with GLP-1s and that some studies reported improvements in sperm morphology, cholesterol, and testosterone in specific settings.
Explain that most reproductive benefits observed are likely secondary to weight loss and improved metabolic health; the possibility of a direct reproductive-axis effect remains unproven.
Consider addressing obesity and metabolic dysfunction as first-line interventions in men with obesity-related low testosterone, reserving testosterone replacement for cases where primary hypogonadism or persistent symptomatic hypogonadism is confirmed and weight/metabolic interventions are insufficient.
Recognize current evidence is limited and evolving; stay alert for larger trials that may clarify indications, risks, and benefits related to male reproductive outcomes.
Randomized clinical trials summarized by researchers in Coventry indicate that GLP-1s can be used in men with obesity without apparent adverse effects on reproductive hormones or sperm quality, and in some trials were associated with improved sperm morphology, cholesterol, and increases in testosterone in men with obesity-related low testosterone. The evidence supports an approach that treats underlying weight loss and metabolic dysfunction to restore hormonal health and preserve fertility. However, the small number and heterogeneity of trials mean larger, well-designed studies are required before GLP-1 receptor agonists can be recommended specifically for male infertility or hypogonadism. As always, clinicians should provide evidence-based counseling about these medications when discussing treatment options with patients.