All you need to know about gestational diabetes (GDM)

By Dr. Dineshani Hettiarachchi Sirisena  

Pregnancy is a time of change that can impact the health of both an expecting mother and their unborn child. Gestational diabetes has been recognised as a leading maternal health concern worldwide. Brunch spoke to Consultant Physician Dr. Jayamalee Jayaweera (MD, MRCP) to explore some of the concerns regarding this condition. 

What is gestational diabetes?

Gestational Diabetes Mellitus (GDM) is diabetes that develops during pregnancy. It usually disappears after birth. We need our pancreas to produce enough insulin to handle the glucose levels in the body, but as we know, during pregnancy, a lot of changes take place within the body. Along with the physical signs, hormonal changes make it hard for your body to handle insulin and sugar and this can put women at an increased risk of insulin resistance. Some women cannot produce enough insulin to overcome this resistance. Therefore, as a result, the sugar levels rise, leading to gestational diabetes. Gestational diabetes can cause problems for both mother and baby during pregnancy and after birth. These risks can be reduced if GDM is identified early and treated properly.

Current trends in GDM 

High blood glucose in pregnancy may affect about one in every six pregnancies worldwide. The numbers may vary in different countries depending on the population and how it is diagnosed. GDM is exceedingly associated with obesity. The risk of having GDM can be fivefold higher in an obese woman when compared to non-obese women. Obesity is a major public health problem that is expected to rise even further. We know obesity and being overweight are major concerns nowadays among children, teens, and young adults in Sri Lanka. We could anticipate the number of women having diabetes during pregnancy to rise at an alarming rate in the future, stated Dr. Jayaweera.

What are the risk factors associated with gestational diabetes?

Any woman can develop gestational diabetes during pregnancy, but you have an increased risk if you are obese/overweight, have a family history of diabetes, if you had a large baby in your previous pregnancy, or had GDM in your previous pregnancy. Mothers who are older than 40 years, or women who have Polycystic Ovarian Syndrome (PCOS) are also among high-risk groups for developing GDM. Being South Asian itself puts Sri Lankan women at a higher risk of developing GDM due to multiple reasons such as maternal age, socioeconomic status, ethnicity, body composition, screening approaches, and diagnostic values. Even a woman of South Asian ethnicity born in a developed country like the UK will still be considered as having a higher risk of developing GDM. Hence, in the UK all pregnant South Asian women will be screened for GDM.

How will GDM affect the mother and the baby?

Most women with GDM undergo a normal pregnancy and have a healthy baby. However, it may potentially cause serious short- and long-term consequences to the baby and mother. 

The baby may grow bigger than usual. We shouldn’t consider this as healthy growth. This may lead to difficulties during delivery, putting the mother and baby at risk. The baby’s shoulder might get stuck during labour. It increases the likelihood of caesarean section and assisted deliveries. The baby may need to be delivered prematurely before the 37th week of pregnancy. The baby may have low blood sugar after birth or yellowing of eyes or skin once he or she is born. Even though rare, unfortunately, there is a risk of stillbirth as well. Additionally, 40-60% of mothers who had gestational diabetes in their pregnancy go on to develop type 2 diabetes later in life. GDM has been called a ‘marker,’ or ‘stress test,’ for future diabetes, though it is not considered as a cause. We also know that children of mothers who had gestational diabetes are at a higher risk of developing obesity, type 2 diabetes, and high blood pressure when they grow up, stated Dr. Jayaweera.

Tests to diagnose GDM

The diagnosis is made with a special test called the Oral Glucose Tolerance Test (OGTT). You will be asked to do a blood test in the morning after fasting (except for water) for 8-10 hours. Then you will be given a glucose drink and another blood test will be taken in 1-2 hours. You must rest during this period. Depending on the results of these two tests your doctor can diagnose whether you have GDM or not. 

What are the blood sugar targets in GDM?

If you are diagnosed with GDM you will need blood sugar tests more often to make sure you remain within target values. Blood sugar targets in pregnancy are tighter than non-pregnant values for any diabetes.

To minimise complications for yourself and the baby from any type of diabetes during pregnancy, blood sugar levels should be maintained as follows:

• Fasting and before meal blood glucose concentration: <95 mg/dL (5.3 mmol/L)
• One-hour post meal blood glucose concentration: <140 mg/dL (7.8 mmol/L)
• Two-hour post meal glucose concentration: <120 mg/dL (6.7 mmol/L)

Can GDM be prevented?

Unfortunately, it can’t be prevented. However, there are certain steps that can be taken to reduce risk. This includes maintaining your weight, eating nutritious meals, and keeping active especially before you conceive. 

Treatment options 

The first step of treatment for gestational diabetes is eating right. To help you achieve these changes you can discuss them with your physician, obstetrician, dietitian, or nutritionist. The general advice for a healthy pregnancy diet would be:

• Eat three small-sized meals and three to four healthy snacks
• Eat every two to three hours to space food evenly throughout your day
• Make sure you take dinner early – before 7 p.m. 
• Reduce starchy food – e.g.: bread, rice, roti, paratha, pasta, potato, cereals
• Choose whole grains over refined grains and food with a low glycaemic index over a high glycaemic index when possible
• Avoid sweet desserts and sweetened drinks. This includes cakes, biscuits, ice cream, donuts, jams, and jellies
• Avoid adding sugar to your food or drinks
• Fruits and fruit juices – Limit fruit servings to a small piece of fruit at a time
• Many vegetables are low in sugar and carbohydrates. Include plenty of salads, green leaves, green vegetables, tomatoes, onions, mushrooms, and other vegetables you enjoy. Half of the plate at your meals can be non-starchy vegetables, salads, and leaves
• Include protein with limited saturated fat such as chicken and fish. Other high protein foods like cheese, milk, eggs, food like nuts, seeds, pulses such as chickpeas, beans, and lentils are also good for you and your baby
• You must not skip any meals

Exercise will help reduce blood sugar levels after meals. If you were regularly exercising before, you should continue after being diagnosed with gestational diabetes. 

If your sugar levels do not get under control with diet and exercise, your doctor would start you on medication. Metformin is the only tablet medication we can give for diabetes in pregnancy. It has not been shown to harm the baby and is therefore considered safe. Another option is insulin, which is an effective and safe injection that can be given during the pregnancy as it doesn’t cross the placenta to reach the baby. 

What would happen after birth?

It is important to feed your baby as soon as possible after birth (within 30 minutes) and then at frequent intervals (every 2-3 hours) until the baby’s blood sugar levels are stable. Yours and your baby’s blood sugar levels will be checked in the hospital to make sure they remain normal. All treatment you were taking for blood sugar control will usually be stopped after delivery.

What are the precautions to be taken to prevent long-term implications?

Having gestational diabetes does increase your risk of developing type 2 diabetes later in life. Your doctor will request you to go for blood sugar checks at 6-13 weeks following delivery to make sure sugar levels remain normal. 

It is always advisable to check your fasting blood sugar levels once a year to detect if you could develop diabetes later on. You should follow a healthy diet, lose any excess weight, and exercise regularly to help reduce the risk of developing type 2 diabetes.

If you are planning for another pregnancy in the future make sure you check for diabetes beforehand.

Take home message 

It is important to recognise and treat gestational diabetes to minimise the risk of complications to the mother and baby. In addition, women with a history of gestational diabetes need to be tested for diabetes after pregnancy because of an increased risk of developing pre-diabetes and type 2 diabetes in the years following delivery, concluded Dr. Jayaweera.