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Diabetes Drug Metformin May Damage Sperm!

Posted on 29th March 2022

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A new study, reported on "Science" has suggested that men who take Metformin, a drug prescribed for Type 2 Diabetes, may suffer from damaged sperm.

Specifically, the sperm can suffer from genetic defects affecting the sexual organs of sons, if Metformin is taken long term. The caveat of long term use of Metformin is no encouragement, since this drug is only prescribed for long term use.

The study is an observational meta-study (a study of the results of other studies), which doesn't prove a cause and effect relationship, and the results need to be confirmed by further studies. Nevertheless, the study analysed records from more than 1.1 million babies born in Denmark between 1997 and 2016, which is a large enough sample to be taken seriously.

The article describes the defects as "relatively rare", but I don't think that most people would consider 0.9% to be rare.

The scientists "cautioned men with diabetes against abruptly stopping metformin before trying to conceive", which is an entirely sensible warning.

Another aspect of the report was very worrying. Although Metformin "has been in use since the 1950s", "this is the first large study to rigorously analyze any paternally mediated impact on human birth defects". I wonder how many other drugs are in use which have not been properly studied. There are some parallels here with the Thalidomide scandal (Thalidomide was also sold under the brand-name Contergan, as a treatment for morning sickness, although it has other uses).