New treatment for diabetes in pregnancy is safe

Wednesday, 14 May 2008

An alternative treatment to insulin injections for pregnant women with gestational diabetes has been shown as safe and effective in a new trial led by researchers in Adelaide and Auckland.

A clinical trial of 751 women with gestational diabetes in Australia and New Zealand compared two treatments: insulin injections, and the oral anti-diabetic drug metformin. The results of the trial, published in The New England Journal of Medicine, show that the babies of mothers treated with metformin were no different from the babies of mothers treated with insulin alone, either at birth or at 6-8 weeks of age.

"No serious adverse effects were associated with the use of metformin," says University of Adelaide Clinical Senior Lecturer Dr Bill Hague (Discipline of Obstetrics & Gynaecology).

"More than half the women taking metformin could be managed with tablets alone. If extra insulin was necessary, the dose was less than that required for women taking insulin alone," he says.

Gestational diabetes is a complication in about 5% of pregnancies and is on the increase. Where the diabetes can't be controlled through diet and exercise, insulin therapy is often used to significantly improve the health outcomes for both baby and mother.

"But the use of insulin requires injections and women need to be educated in its use," Dr Hague says. "Insulin therapy can also cause low blood glucose and weight gain in the mother, whereas use of metformin usually returns blood glucose to normal, rather than dropping it too low, and is also associated with maternal weight loss.

"Oral medication therefore can offer considerable advantages. Women in this trial certainly preferred to use metformin rather than insulin.

"To date, however, metformin use in pregnancy remains controversial - before this study there were only two reported small randomised trials comparing metformin with insulin," he says.

The Metformin in Gestational Diabetes (MiG) Trial has been led by Dr Janet Rowan, University of Auckland in New Zealand, and by Dr Hague in Australia. Dr Hague is also a Senior Consultant Physician in Obstetric Medicine at the Women's and Children's Hospital, Adelaide.

The 751 diabetic women were randomly given treatment with metformin (with supplemental insulin if needed) or insulin at 20 to 33 weeks into their pregnancy. The two groups were compared using a number of measures including the presence in the newborn babies of low blood glucose, any respiratory distress, the need for phototherapy, any trauma at birth, their Apgar score (skin colour, heart rate, reflex irritability, muscle tone, breathing) and prematurity. There was no increase in complications after birth from metformin use, compared with insulin therapy.

Dr Hague says the children born within this trial are currently being assessed at two years of age, and further follow-up data are still needed to establish long-term safety.

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