The GRACES trial: comparing ways of treating diabetes in pregnancy

Jane Norman, Rebecca Reynolds, Fiona Denison, Mark Strachan, Claire Alexander, Corrine Love, Robert Lindsay, Fiona Mackenzie, Ed Juszczak, Ben Stenson

Researchers have found that controlling diabetes during pregnancy using a combination of pills is not as effective as treatment with insulin injections.

Women who first get diabetes in pregnancy (known as gestational diabetes) are usually treated first by changing their diet, and then with a drug called metformin that can be taken as a tablet. This helps to control the amount of sugar in the blood so that it doesn't get too high. In pregnant women, this is often still not enough: they also need to inject insulin. This is the hormone that helps us move sugar from our blood into our cells, where it can be used to make energy.

In women who aren't pregnant, diabetes is usually treated with metformin and another tablet, called glibenclamide. We wanted to see if pregnant women could also be treated this way, so that they didn't need to inject insulin.

In a small study, we found that using metformin and glibenclamide together did not work as well as using metformin with insulin injections. Women who took part in the trial also didn't have a preference for swallowing a tablet over injecting insulin. We think that this shows that we should continue to treat diabetes during pregnancy with metformin and insulin injections. However, if women are particularly scared of needles, or if they cannot use insulin, then using a combination of tablets is possible.

Thanks for your interest in our research

Tommy's funds research across the UK investigating the reasons for pregnancy complications and loss. Maternal and fetal research is underfunded and we need your support to continue. There are many small and large ways you can support us, find out more here.


This study takes place in a Tommy's centre and is funded by Tommy's and Chief Scientist Office Scotland

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