When pregnancy causes diabetes

Posted on 1 November 2021

When a healthy woman develops diabetes during pregnancy, it’s known as gestational diabetes mellitus (GDM). It’s a serious condition that must be managed to ensure you – and your baby – are healthy.

When Tina Mostert, 38, was diagnosed with GDM during routine tests in her third pregnancy, she was genuinely surprised. “I’ve always associated diabetes with being overweight, but I’m slim and super-active – I’m a runner, play hockey, and do resistance training – and health-wise, I was feeling great. In fact, I was the leanest and fittest I’d ever been. I hadn’t even developed a sweet tooth during my pregnancy.”

As Dr Wimpie de Lange, an endocrinologist at Mediclinic Bloemfontein, says, it’s not fully understood why some women develop GDM. “When you’re pregnant, the placenta, which connects your baby to your blood supply, produces high levels of other hormones. As your pregnancy advances, the placenta produces increasing amounts of insulin-counteracting hormones. This leads to insulin resistance. Initially the pancreas tries to cope, but in some high-risk patients, the pancreas fails, and this leads to GDM. With GDM, the placental hormones provoke a rise in blood sugar to a level that can affect your baby’s growth and welfare. GDM typically develops during the second and third trimesters of pregnancy.”

GDM is a common condition world-wide, affecting as many as one in five pregnancies in certain population groups.


Risk factors for developing Gestational diabetes mellitus (GDM)

  • Being older than 25 years
  • Having a close family member, such as a mother or father, with Type 2 diabetes
  • Having had GDM in a previous pregnancy
  • Being overweight with a body mass index (BMI) of over 30kg/m2
  • Having polycystic ovarian syndrome (PCOS)
  • Having had complications in a previous pregnancy with a baby larger than 4.5kg, a stillborn baby, or a baby with malformations.

On her doctor’s advice, Tina continued to exercise and immediately changed her diet, cutting out all sugar and most carbohydrates – including rice, bread, butternut, potatoes, corn and peas. “I was also put on medication to help manage my insulin levels,” she says. “I was obviously concerned because GDM can lead to having a bigger than average baby, there can be increased risks associated with a natural birth, and I knew my baby’s blood sugar levels could also be affected.”

According to the Centers for Disease Control and Prevention (CDC) in the US, GDM doesn’t usually have any symptoms. Your medical history and whether you have any risk factors may suggest to your doctor you could have gestational diabetes, but you’ll need to be tested to know for sure.

GDM is a serious diagnosis, as you and your baby have an increased risk of developing Type 2 diabetes and other metabolic conditions later in life. According to an article in the South African Journal of Medicine GDM is one of the leading causes of death for mothers and babies worldwide.  The 2016 South Africa Demographic and Health Survey shows that the prevalence of GDM is rapidly increasing worldwide, possibly because of obesity and the fact that woman are falling pregnant later in life. This is particularly concerning, as South African women are among the most overweight globally.

The good news is that there’s a lot you can do to manage the condition. As Dr de Lange says, you should attend all your prenatal appointments and follow your treatment plan:

  • Check your blood sugar to make sure your levels stay in a healthy range
  • Eat healthy food in the right amounts at the right times and follow a healthy eating plan from your doctor or dietitian
  • Exercise regularly, as this lowers your blood sugar levels, making you more sensitive to insulin so your body won’t need as much.

Your doctor will also check your baby’s growth and development.

According to the CDC, if you’re diagnosed with GDM your blood sugar levels will usually return to normal after your baby is born. However, about 50% of women with GDM go on to develop Type 2 diabetes. You can lower your risk by reaching a healthy body weight after delivery. Visit your doctor to have your blood sugar tested 6-12 weeks after your baby is born and then every 1-3 years to ensure your levels are on target.

Published in Patient Stories

In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.