ENDO 2026 reports GLP-1 drugs do not harm and may help male fertility
A review presented at ENDO 2026 found GLP-1 drugs did not harm and may improve testosterone and sperm quality in men with obesity, though researchers say the evidence base remains small.
Research presented Monday at ENDO 2026, the Endocrine Society's annual meeting in Chicago, found that GLP-1 receptor agonist drugs do not harm male hormones or fertility after long-term use, and may improve testosterone levels and sperm quality in men with obesity-related low testosterone [1]. The findings come from a team at University Hospitals Coventry and Warwickshire and Warwick Medical School in the United Kingdom, who searched medical databases for randomized controlled trials comparing GLP-1 drugs to other treatments or placebo in men ages 18 to 65 [1].
The researchers found five clinical trials that met their criteria [1]. In one, a 24-week study of once-weekly semaglutide showed improvements in sperm shape and cholesterol levels while testosterone and other hormone levels stayed stable [1]. A separate 24-week randomized trial of semaglutide in obese men with type 2 diabetes and hypogonadism, described in a review published in the journal Urology, found normal sperm morphology rose from 2% to 4%, a statistically significant change [2]. That same review noted the trial found no significant differences in some other semen measures, though the full comparison was not detailed [2].
A second trial cited by the Endocrine Society team looked at liraglutide over 16 weeks in men with obesity and low testosterone tied to excess weight. Those men saw increases in testosterone and related hormones, with overall health outcomes described as better than testosterone replacement therapy alone [1]. The Urology review, based on a broader search through May 2025, identified 16 clinical studies in total and described the evidence as heterogeneous, meaning results varied study to study [2]. That review also pointed to preclinical work in obese and diabetic rodents showing GLP-1 drugs improved sperm production and hormone profiles, and noted that GLP-1 receptors have been found directly on human sperm and testicular tissue [2].
Pratibha Natesh, M.B.B.S., M.R.C.P., M.Res., the endocrinologist who led the Endocrine Society-presented study at Warwick Medical School, said the findings support treating the root cause of low testosterone in men with obesity rather than defaulting to testosterone replacement. "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," Natesh said [1].
Why it matters for patients
For men with obesity who have low testosterone, this research suggests GLP-1 drugs are not a threat to reproductive health and may help hormone levels recover as weight and metabolic health improve [1]. That matters because some men have wondered whether weight-loss or diabetes drugs could interfere with fertility or sexual function. Both sources agree the drugs appear safe on this front, but they diverge on how strong the evidence for direct fertility benefit is. The Endocrine Society summary, based on five trials, frames the results as encouraging early evidence [1]. The Urology review, drawing on 16 studies and rodent data, is more cautious, calling clinical evidence "limited" and the results across studies "heterogeneous" [2].
Both research teams stress that GLP-1 drugs have not been tested or approved specifically as treatments for male infertility or hypogonadism [1] [2]. Natesh noted that most of the reproductive benefits observed so far are likely indirect, tied to weight loss and better metabolic health rather than a direct effect on the reproductive system [1]. Larger, better-designed studies are still needed before firm conclusions can be drawn [1] [2].
What happens next
No new trials or regulatory reviews tied to male fertility were announced alongside this presentation. The Endocrine Society summary and the Urology review both call for larger prospective studies, but neither source gives a timeline for when such research might begin or report results [1] [2].
Sources
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