Weight-loss drugs may also help boost men’s fertility, study finds

A medicine distributor displays Mounjaro (tirzepatide) self-injecting GLP-1 prefilled pens at his office in Thane, India - (AFP via Getty Images)

The current generation of weight-loss drugs prescribed to treat diabetes and obesity may also come with an added advantage of improving fertility in men, a new study suggests.

In recent years, glucagon-like peptide 1 (GLP-1) drugs have gained popularity for their ability to help users shed pounds and lead a healthier life.

A growing body of studies has also found that these weight-loss drugs have additional potential benefits against multiple conditions, including dementia and cancer.

Previous research has shown that obesity is strongly associated with dysregulation of the male reproductive system, particularly the quality of sperm.

While GLP-1 drugs have been proven to have positive effects on obesity, their effects on male reproductive hormones and fertility remain uncertain.

Now, a new review of studies finds that GLP-1 drugs may boost testosterone levels and improve quality of sperm in men with obesity.

While evidence for these benefits is preliminary, researchers say the findings highlight the need for more studies to assess the male reproductive outcomes of GLP-1 drugs.

In the research review, scientists from Warwick Medical School in the UK assessed existing studies for clinical trials of GLP-1 drugs, which also documented testosterone levels of its male participants.

For instance, in one of the five studies reviewed, 30 men who had low testosterone levels underwent either testosterone replacement therapy (TRT) or were given a GLP-1 drug.

Scientists found that at the end of 16 days of treatment, both the groups of men showed an increase in testosterone levels.

Another study treated 25 men with type 2 diabetes and hypogonadism with either a GLP-1 drug or TRT, and found that in 24 weeks both groups had higher testosterone levels.

While the TRT group experienced an even higher level of testosterone post treatment, sperm quality significantly improved in the GLP-1 drug group, researchers say.

The ratio of sperm with perfect shape and size went from 2 per cent at the start of the study to 4 per cent by the end of the trial, scientists found.

Within the context of weight loss, the latest review observed that GLP-1 drugs “may improve reproductive hormones and semen parameters in obese hypogonadal men”.

“However, evidence remains limited and heterogeneous, underscoring the need for larger randomised clinical trials explicitly powered to assess male reproductive outcomes,” scientists wrote in study presented at the Endocrine Society’s annual meeting in Chicago, Illinois.