Men’s use of diabetes drugs just before conception linked to 40% increase in birth defects

Metformin, a first-line drug for Type 2 diabetes treatment, has been linked to increases in birth defects when taken before conception.

A recent study shows that this treatment, when used within a three month period of conception, was linked to a 40% higher risk of birth defects. 

According to KETV, the study was published Monday in the journal Annals of Internal Medicine. The study utilized national registries to follow over a million births between 1997 and 2016 and compare the risk of major birth defects based on parental exposure to diabetes medications. The study included children born to women under age 35 and men under 40.

According to the study, birth defects in babies born to men with type 2 diabetes but were not taking metformin occured at a frequency of 3.1%. The frequency among those birth defects in children born to men taking metformin for type 2 diabetes was 4.6%.

Men taking metformin were considered if they had taken it within three months of conception, as that is how long it takes fertilized sperm to fully mature.

The study found that genital birth defects seen only in males were the only birth defect to be a statistically significant increased risk with metformin use. When metformin was taken by men before or after the three-month maturation period there was no increased risk of a birth defect in their child.

Researchers did not find a significant correlation between birth defects and paternal exposure to other diabetes medications besides metformin.