Maternal and neonatal outcomes are similar in women treated with metformin, insulin, or diet and lifestyle modification for their gestational diabetes (GDM), Australian research shows.
A retrospective case control study at the Royal North Shore Hospital, Sydney, matched 83 women taking metformin on a 1:1 basis with women receiving insulin or diet and lifestyle modification alone.
Mode of delivery was similar in the three groups of women, but women treated with glucose-lowering therapies were delivered at a slightly earlier gestational age than women managed with lifestyle measures.
Infants born to women in each group were of similar birth weight although large-for-gestational-age infants were more likely in women treated with pharmacotherapy for GDM.
Infants of women treated with glucose-lowering therapies were also more likely to experience neonatal hypoglycaemia.
There was no difference between the groups in the incidence of shoulder dystocia, respiratory distress, jaundice, NICU admission, birth injury, birth defect or neonatal death.
The researchers concluded metformin is a useful alternative to insulin in the management of GDM.
Professor Greg Fulcher, from the Department of Diabetes, Endocrinology and Metabolism at Royal North Shore Hospital, told the limbic the use of metformin remained controversial in Australia despite being widely used in some countries including South Africa and the UK.
“There is a very grey zone about diabetes in pregnancy; it’s been a very contentious area for a long time.”
“I think everyone is pretty clear that in the pregnancy itself, there doesn’t seem to be any problems whatsoever. I think everyone completely agrees about that. I think if you look at the follow-up of the offspring, there doesn’t appear to be any problems in the short term.”
However there was ongoing debate about what was an acceptable longer-term follow-up period for the infants given that metformin crossed the placental barrier.
“In Australia I think we have a conservative Diabetes in Pregnancy Society and there’s nothing wrong with that but the executive of that group are of the opinion that they’d like to see 20 or 30 year follow up before they will be happy using the medication.”
“The UK and other countries have accepted that the current lengths of follow-up are more than reasonable.”
There was a very wide range of practice in Australia, according to Professor Fulcher.
“We’ve seen nothing to date in our own experience and we keep monitoring the literature very closely and have still not seen anything in the literature to raise our concerns or to review what we do.”
“Some people would prefer insulin which means multiple daily injections while others would say they prefer to take a medication. The reality is that if we start treating women early in pregnancy with metformin, we still actually need to start adding in insulin in about half of those women.”
“So it avoids insulin in about 50% of the people who have agreed to use it and avoids insulin for a few months in the other 50%,” said Professor Fulcher.