Dad's Use of Diabetes Med Metformin Won't Raise Birth Defect Risk

October 17, 2024

A new, reassuring study finds that men can take the diabetes drug metformin without worrying that their offspring will suffer from birth defects.

Recent research raised concerns that metformin could promote birth defects in children by damaging the quality of a man’s sperm.

But this study of more than 3 million pregnancies, published Oct. 16 in the BMJ, concluded those fears are unfounded.

The new study “found no significant association between paternal metformin use during the period of sperm development and congenital malformations in offspring,” concluded the research team led by senior researcher Hedvig Nordeng, a professor of pharmacy with the University of Oslo in Norway.

Metformin helps control blood sugar levels by decreasing the amount of glucose absorbed from food and made by the liver, according to the National Institutes of Health.

A 2022 Danish study found a 40% increased risk of birth defects in the children of men taking metformin, researchers said. The drug is known to cause lower testosterone levels and potentially diminished sperm quality.

To further test this link, researchers analyzed data on nearly 620,000 babies born in Norway between 2010 and 2021 and more than 2.5 million babies born in Taiwan between 2004 and 2018.

In Norway, birth defects were found in about 5% of babies born to fathers taking metformin, compared with 4% of those whose dads didn’t use the drug, a nonsignificant difference.

Similarly, birth defects occurred in about 3% of all Taiwanese children, whether or not their dads used metformin.

After looking specifically at fathers with type 2 diabetes and controlling for other factors, researchers found no increased risk at all of birth defects related to metformin.

“These results provide reassurance and can assist clinicians in making informed treatment decisions when selecting metformin in the treatment of type 2 diabetes mellitus among men who are planning a family,” the Norwegian researchers concluded in a journal news release.

In an editorial that accompanied the study, Australian researchers welcomed the findings.

“For some, these findings may not completely lay to rest concerns raised by the Danish analyses, and further confirmatory studies are worthwhile,” the Australian team noted. “At the very least, however, these findings provide some reassurance for clinicians, and for fathers-to-be prescribed metformin preconception.”

More information

The National Institutes of Health has more about metformin.

SOURCE: BMJ Group, news release, Oct. 16, 2024

Diabetes: Type II Birth Defects: Misc.