Men treated with GLP-1 receptor agonists showed significant increases in both total and free testosterone levels, independent of age and baseline BMI, according to new findings.
The improvements were also not solely explained by weight loss.
“GLP1s have rapidly become one of the most important therapeutic classes in metabolic medicine. And while their effects on glycemic controlling with reduction were established, much less is known about their impact in men's health,” said study author Andrés Heriberto Guillén-Lozoya, MD, a post-doctoral research fellow at the Mayo Clinic. “This is particularly important because obesity, insulin resistance, and metabolic syndrome are strongly associated with functional hypoganism and reduced testosterone levels in men.”
Guillén-Lozoya presented the findings of the study at the 2026 American Urological Association annual meeting.
Improvements in testosterone in obese patients is often attributed to weight management and potentially involving changes in insulin sensitivity, inflammation, and restored hypothalamic-pituitary-gonadal axis function.
“With that in mind, we aimed to evaluate changes in total and free testosterone after the initiation of GLP-1 therapy,” said Guillén-Lozoya.
In a retrospective analysis, Guillén-Lozoya and colleagues analyzed obese men who had received semaglutide or tirzepatide and had pre and post treatment testosterone measurements from October of 2018 to October of 2025. In their primary analysis, they evaluated changes in total and free testosterone using pair nonparametric testing and performed an adjust linear analysis that controlled for age and BMI.
They identified paired total testosterone data in 1,629 men and free testosterone data in 1,216 men. At baseline, patients with lower BMI tended to have higher testosterone levels overall, which is consistent with prior literature.
The study’s endpoint was absolute changes in total and free testosterone.
“After GLP1 therapy, however, we observed a significant improvement in both total and free testosterone levels,” said Guillén-Lozoya.
Median total testosterone increased from 320 to 419 ng/dL and median free testosterone increased from 9.0 to 10.4 ng/dL (P<0.001 for both). After adjusting for age and BMI, total testosterone increased by a median of 97.6 ng/dL, and similarly, free testosterone increased by 1.3 ng/dL (P<0.001 for both).
Importantly, he noted, the findings remained statistically significant even after adjustments were made for age and baseline BMI in the mix effect model. “One of the most interesting finding from our study was that changes in testosterone were not directly correlated with BMI reduction alone,” noted Guillén-Lozoya. “What this suggests is that the hormonal improvement observed may not be explained solely by weight loss. Our leading hypothesis is that the testosterone improvement is slightly multi-factorial.
“Weight reduction and reduced adiposity probably contributed significantly, but additional mechanisms may also be involved, such as improved insulin sensitivity, reduced inflammation, reduced aromatization for the adipose tissue, and potentially a restoration or improvement of the hypothalamic-pituitary-gonadal axis," he noted.
Guillén-Lozoya also hypothesized that GLP1 drugs may eventually emerge as a adjunctive strategy for men with functional hypogonadism that is related to obesity and metabolic disease. “However, I will not frame them as primary or as a replacement for standard hypoganism management, but rather they may function as an aid or as a disease modifying metabolic therapy in selective patients,” he said.
He acknowledged that the study had limitations, notably that this was a retrospective analysis. Testosterone measurements were not standardized by timing were not standardized by timing, and that causality cannot be established. Residual confounding also remains plausible.
Nevertheless, the findings suggest that GLP1 may have favorable effects in these male patients, particularly in obese and metabolically complicated men. “"As the use of these medications continues to expand worldwide, understanding their broader implications in men's health will become increasingly important,” he concluded.
Guillén-Lozoya had no disclosures. No outside funding was disclosed.
Guillén-Lozoya AH, et al "Testosterone levels improve in men under GLP-1 receptor agonist therapy" AUA 2026; Abstract PD26-01.
Image by N Universe / Shutterstock
