Researchers at the University of Galway say a new study into gestational diabetes shows a commonly used drug provides a "safe and effective" way to treat the condition.

Metformin is widely prescribed for Type 2 Diabetes, but there have been concerns about how it might impact preterm birth and infant size.

In a randomised trial involving more than 500 expectant mothers, the study found no differences in adverse neonatal outcomes, among those who were treated with the medication during pregnancy.

Consultant Endocrinologist Professor Fidelma Dunne said the research was undertaken in an effort to determine the optimal management approach following a diagnosis of gestational diabetes.

This condition, characterised by elevated blood sugar levels during pregnancy, is estimated to impact almost 3 million women worldwide every year.

Prof Dunne said the use of insulin to manage it was associated with some challenges, leading researchers to examine other treatment options.

She said the study showed metformin was an "effective alternative" for managing gestational diabetes.

It found women prescribed metformin were 25% less likely to need insulin, and when insulin was necessary, it was started later in the pregnancy.

The research also found delivery occurred at the same mean gestational age (39.1 weeks) in both those on the drug and other study participants who were given a placebo.

There was no evidence of any increase in preterm birth among those who received metformin.

And while there was a slight reduction in infant length, there were no other significant differences in baby measurements.

Prof Dunne has described the results as "a significant step forward for women with gestational diabetes".

The findings from the trial are being published in the Journal of American Medical Association.