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What is the GUARD MEC study?

Within your gut there are trillions of microbes that are called the ‘gut microbiome’. We know that these bacteria are very important to your health and wellbeing. They play a key role in digesting your food, and they are involved in many other processes, including your metabolism, body weight, immune system, amongst others.

In this study we want to find out a bit more about how some medicines affect the gut microbiome in women with gestational diabetes mellitus (GDM). We would like to know how this affects their hormonal system, blood sugar (glucose) and blood fats (lipids). By doing this research we hope to better understand the causes of these conditions. This may help doctors to be able to advise women about future lifestyle choices they may want to make in areas such as food.

Who can take part?

The study is open to

  • Participants already enrolled in the main GUARD trial
  • Patients taking metformin as standard of care
  • Patients managing GDM with diet and lifestyle changes
  • Pregnant women without GDM

What will happen to me if I take part?

Once you agree to take part, we will ask you to sign a consent form and attend one study visit. Your visit will take place around the time you are 36 weeks’ pregnant. We will ask you to fast overnight, for at least 8 hours, before you come to the hospital. You can have plain tap water or tea/coffee without milk/sugar to drink. When you come to the hospital, we will put a small tube (cannula) in the back of your hand or arm. This is the same that are used as part of clinical care, such as the ones used for anesthetics or to give fluids through a drip. We will use the cannula to take the blood before and after a breakfast, which we will provide (the first blood sample will be taken shortly after you arrive and while you are still fasting and 15 min, 1 and 2 hours after you have eaten breakfast). In total we will take 4 blood samples. This is roughly 6 tablespoons of blood (86 ml). The session will take approximately 3 hours.

What are the possible risks and benefits?

Apart from giving the blood samples, there are no disadvantages of taking part in the study. Having the cannula inserted or having blood taken may involve some discomfort to you, but this will be minimal. There is a risk of bleeding and bruising around the puncture site, but this is very rarely serious. There is no risk to your baby from any part of the study.

There is no direct benefit to you. However information from the study may give knowledge in the future about complications of pregnancy. This may reduce illness and possibly death both for mothers in pregnancy and their babies.

We will give you a £50 Love2shop voucher as recognition of your contribution and to thank you for your time.

Which NHS Trusts are taking part?

The following hospitals are currently open to recruitment to this study:

  • Guy’s and St Thomas’ NHS Foundation Trust
  • Imperial College Healthcare NHS Trust

Who is organising and funding the research?

Professor Catherine Williamson is leading this study. The trial is being funded by Jon Moulton Charitable Foundation.

Who has reviewed this research?

This trial has been reviewed and given favourable opinion London Westminster Ethics Committee and has approval from the Health Research Authority.

Project status: Ongoing
GUARD MEC logo with name

Project websites

Contact us

Departments of Women and Children’s Health
10th Floor North Wing
St Thomas' Hospital
Westminster Bridge Road
London SE1 7EH