GLP-1 weight-loss drugs may improve male fertility

GLP-1 drugs may help to improve male testosterone levels and sperm count, preliminary research suggests.

Glucagon-like peptide 1 receptor agonists (GLP-1 drugs), such as Ozempic and Wegovy, are widely used to treat obesity and type 2 diabetes. Researchers from Warwick Medical School analysed data from clinical trials of GLP-1 drugs to evaluate the treatment effect on the male reproductive system.

'Obesity is increasingly prevalent and is strongly associated with dysregulation of the male hypothalamic pituitary gonadal (HPG) axis, functional hypogonadism and impaired semen quality,' said Dr Pratibha Natesh, who presented the findings at the Endocrine Society's annual meeting in Chicago, Illinois. 'GLP-1 [drugs] do not appear to acutely suppress the male HPG axis and may improve reproductive hormones and semen parameters in obese hypogonadal men, largely within the context of weight loss.'

Dr Natesh and her colleagues undertook a systematic review of data from five existing trials that involved men aged 18-65 years receiving a GLP-1 drug compared with appropriate controls. Short-term treatment in healthy men showed no meaningful changes in hormone levels or semen quality. In obese men with functional hypogonadism (where the testes make insufficient sperm or testosterone), several long-term GLP-1 drug treatments increased testosterone levels and improved sperm morphology, concentration and total count.

'The relationship between obesity, metabolic health, and fertility has been well established for many years,' said urologist Dr Philip Werthman, from the Centre for Male Reproductive Medicine in Los Angeles, California, who was not involved in the study. 'In men, we commonly see lower testosterone levels, functional hypogonadism, erectile dysfunction, and poorer semen parameters,' he told Medical News Today.

Unlike testosterone replacement therapy, which treats obesity-related low testosterone but suppresses sperm production, the study found that GLP-1 drugs did not appear to suppress normal reproductive signals.

'Several studies have demonstrated improvements in testosterone levels and certain semen parameters following treatment with GLP-1 receptor agonists,' said Dr Werthman. 'Obesity-related hypogonadism is one of the most common reversible causes of low testosterone that I see in practice... One of the most important clinical distinctions is that GLP-1 therapies appear fundamentally different from testosterone replacement therapy for men who wish to preserve fertility.'

This research has not yet been peer-reviewed. The authors noted that the evidence 'remains limited and heterogeneous, underscoring the need for larger [clinical trials] explicitly powered to assess male reproductive outcomes.'