Gestational Diabetes Mellitus (GDM) is a condition that arises exclusively in pregnancy. Unlike other types of diabetes, it will usually go away on its own, with blood sugar levels returning to normal soon after birth. Very rarely it may be identified in the first trimester blood tests, in which case it is likely you actually had diabetes prior to your pregnancy.

What is Gestational Diabetes?

Outside of pregnancy, when you eat carbohydrates, these are released as glucose in to your blood stream to be used as energy. Your body has a natural mechanism for reducing these levels and helping it to be stored in cells for use at a later date, this is the hormone insulin.

During pregnancy, hormones produced by your placenta will make the insulin you produce less effective, meaning your body produces more insulin. Pregnancy creates a natural state of insulin resistance. Your body will produce more insulin to compensate but if your body is unable to produce these levels of insulin, it can lead to hyperglycemia (high blood sugar levels) or glucose intolerance and ultimately GDM.

If left untreated, gestational diabetes can present significant risks for both you and your baby, so it’s important to catch it early, manage your blood glucose levels and attend regular checkups throughout your pregnancy. In this post, we’ll talk about common risk factors for gestational diabetes, to ensure that you have access the most up to date, evidence-based information for an empowered pregnancy.

Risk Factors for Gestational Diabetes

We still don’t know the reason why some women develop GDM and others don’t, but we do know that one in 10 women will develop gestational diabetes during their pregnancy, and there are certain factors which will make developing this condition more likely:

  • Obesity (BMI >30)
  • Ethnicity (Afro-caribbean, SE Asian, Middle Eastern & Chinese populations have a higher risk)
  • Having experienced GDM in a previous pregnancy (around 40% chance of developing it in a subsequent pregnancy)
  • Family history in a first degree relative (parent or sibling)
  • A previous baby weighing more than 4.5kg (9lb 9oz)

How Gestational Diabetes is Diagnosed and Treated?

If you have any of the risk factors listed above, you’ll be referred for a blood test between 24-28 weeks. You may also be referred for this test if your baby is measuring larger than it should on an ultrasound scan or if glucose is detected in your urine. It’s not the most pleasant of tests, but is fairly quick and something that is important to reach a diagnosis. Two blood tests will be taken, the first after you’ve had nothing to eat in the morning, the second will be taken 2 hours after you’ve had a sugary drink (which can taste a bit sickly. The purpose of the test is to see how your body copes with processing a high dose of sugar and if you are above the threshold, you’ll be diagnosed with GDM.

Receiving a diagnosis of GDM, may be upsetting, especially if you have a previously low risk pregnancy. It will mean that you will suddenly have a number of interventions and that you’ll be seen and monitored in a specialist clinic with a dietician, an obstetrician and in some cases an endocrinologist.

You’ll be asked to monitor your blood sugars several times a day by pricking your finger, and record what you’re eating to try and work out whether your sugar levels can be controlled with with lifestyle measures such as diet and exercise, which is the first step of management. If your levels are still high despite these interventions, you will likely be advised to start a medication called metformin and if levels are still rising sometimes insulin injections will be recommended.

You may find it frustrating and upsetting, if a medication is prescribed for you, especially if you’re trying your hardest to control your levels. It’s really important to not blame yourself if you’re doing all you can with dietary modifications. Sometimes despite your best efforts additional help is needed. This is not a failing on your part, as the pregnancy grows, the insulin resistance also increases and so medication ultimately may be needed.

You would normally be recommended to have additional scans to monitor your baby’s growth and depending on the size of your baby and how well your blood sugar is controlled, your medical team will more than likely recommend an earlier delivery (before 41 weeks at the latest) as we know that there’s an increased risk of still birth in the baby’s of women with GDM at later gestations.

A vaginal delivery is still very possible and not contraindicated, but if your baby is thought to be very big, we may also have a discussion about a caesarean birth, as there is an increased risk of something called a shoulder dystocia (this is considered an emergency and is occurs during delivery, when the shoulder becomes stuck after the head has delivered).

What to Expect After Giving Birth?

As we mentioned above, gestational diabetes will normally go away after giving birth. To make sure, you will need to have a blood test six weeks after you deliver to check for type 2 diabetes (T2DM). This is because there is a significantly increased risk of you developing T2DM in later life (around 60%), being around two to three times more likely to develop it in the 5 to 10-year period after your pregnancy, so it’s really important to have annual checks for diabetes and also maintain a healthy weight and diet to reduce your chances of developing this condition.

Following the immediate period after birth your baby may have some difficulty controlling their blood sugars as they have all the excess insulin floating around their body from pregnancy and therefore may have very low sugars (hypoglycaemia). So your baby will need to have their blood sugars monitored regularly for 24-48 hours after birth. We also know that baby’s of mum’s who had diabetes in pregnancy have have a higher risk of obesity. It may require a slightly extended stay in hospital but your medical team will provide you with all the information necessary for ensuring that gestational diabetes has as little impact on your baby’s life as possible.

How You Can Minimise Your Chances of Gestational Diabetes?

While risk factors such as family history and ethnicity can’t be modified, it's important to remember that they do not necessarily mean you will develop gestational diabetes. If you do fall into the high-risk category, there are some steps you can take in order to prevent developing this condition in pregnancy; it’s not necessarily a foregone conclusion.


First of all, educate yourself about this condition. Your hospital should help with this. Most GDM clinics involve input from a dietician, a diabetic specialist nurse and an endocrinologist, as well as your obstetrician. Understanding what’s happening in your body and why controlling your sugar levels is important should make it easier, empowering you to manage this yourself.

Maintaining a normal BMI

You can also aim to maintain a ‘normal’ BMI. Body Mass Index is a ratio of weight and height, and is a less than perfect system, but a BMI of between 19 and 25 generally equates to a healthy target. Trying to avoid putting on more than the recommended amount in pregnancy will help prevent gestational diabetes. Your healthcare team will be able to advise you if you have any concerns regarding your weight during pregnancy.


We know that a regular exercise routine pre-pregnancy and in early pregnancy will help reduce your risk of developing GDM and maintaining this throughout pregnancy will also be beneficial. A 2015 systematic review of 2,800 women, published in BJOG, found that exercising in pregnancy reduced the risk of developing diabetes by 30% and up to 36% in those maintaining exercise throughout pregnancy. This was found to have most benefit if women practice a variety of stretching, strength and cardiovascular activity. Yogaprovides great benefits during pregnancy and helps contribute to this exercise target.


A balanced and healthy diet is essential in both preventing and managing gestational diabetes.

  • Avoid heavily processed foods, those with a high GI index, i.e. refined sugars and those that release their energy very quickly (white bread, pasta and rice).
  • Instead eat foods with a high fibre content, so lots of grains, fruit and veg will be really beneficial.
  • Aim to combine protein or fats with carbohydrates during a meal, this will help with slowing the release of glucose in to the blood.
  • Have small, regular meals throughout the day, in place of eating fewer big meals, can also be helpful in maintaining a well-controlled blood sugar level.

We realise that coping with a diagnosis like this can be hugely overwhelming at a time when you are doing your best to care for your growing baby and for those who already suffer from depression or anxiety it can make it worse. Although this is a condition that needs to be closely managed, it’s important to remember that your medical team are at hand to help try not to overly focus on high readings and let them know if you need further support.

For more information about gestational diabetes, sign up to our newsletter to be the first to know about our new Gestational Diabetes webinar when we lauch this next month and check out these additional resources.


G Sanabria-Martínez, A García-Hermoso, R Poyatos-León, C Álvarez-Bueno, M Sánchez-López and V Martínez-Vizcaíno. Effectiveness of physical activity interventions on preventing gestational diabetes mellitus and excessive maternal weight gain: a meta-analysis. BJOG: an International Journal of Obstetrics and Gynaecology DOI: 10.1111/1471-0528.13429

A comparison of follow-up rates of women with gestational diabetes before and after the updated National Institute for Health and Care Excellence guidance advocating routine follow-up, and the association with neighbourhood deprivation SEBASTIAN WALSH, 1 MAHMOUD MAHMOUD, 2 HTWE HTUN, 3 SHEENA HODGETT, 4 DAVID BARTON5

Br J Diabetes 2019;19:14-18