What is gestational diabetes?
Posted on 31 October 2019
Gestational diabetes means you have high blood sugar levels during pregnancy – but is it a precursor of Type 2 diabetes? And will it affect your baby?
When a woman who is pregnant begins to show evidence of having abnormal blood glucose levels, this is known as gestational diabetes: a form of the disease that first makes itself known during pregnancy. Importantly, gestational diabetes affects women who did not have diabetes before they became pregnant.
How does it develop? Who is at risk? Are there early warning signs that could help doctors reverse the condition? And will your child be born with diabetes?
“We say a pregnant woman has gestational diabetes when she shows blood sugar levels that are higher than normal,” explains Dr Elmo Pretorius, a specialist physician and endocrinologist at Mediclinic Vergelegen. “These values are never typical diabetic values; instead, in a person who is not pregnant, these are values that would indicate a state of prediabetes.”
A person who is considered prediabetic will have higher blood sugar levels than the general population, but not high enough – yet – for a verified diabetes diagnosis. Typically, people with prediabetes show no symptoms, but these higher-than-usual blood sugar values are almost always a marker of the beginning stages of diabetes development.
There are two common tests used to measure sugar levels in the blood, says Dr Pretorius: a fasting blood sugar test, which involves a blood sample being taken after an overnight fast, and an oral glucose tolerance test, where you will be given a sugary liquid to drink, and have your blood sugar levels tested periodically over the next few hours. To confirm a diagnosis of prediabetes, doctors will use a fasting blood sugar level from 5.6 to 6.9mmol/L, or an oral glucose tolerance reading of over 7.8mmol/L after two hours.
“For a long time, gestational diabetes was misunderstood, or perhaps underestimated,” says Dr Pretorius. “We thought it was something that happened to some women, but not others, and it was more of a complication of pregnancy than anything else. We now know that’s not the case.”
To understand how diabetes develops in pregnant women, Dr Pretorius says we first need to picture the role of insulin – an essential hormone produced by the pancreas to help transport blood glucose into and generate energy within the cells of your body. “When we eat, the pancreas releases insulin into the blood,” explains Dr Pretorius. “In response, the pancreas produces insulin to process and reduce blood glucose to keep it within a safe or normal range.”
But during pregnancy, a woman’s blood glucose is naturally shunted out of the mother’s system and into that of the foetus due to hormones causing the mother to become insulin resistant, he says. “This can put pressure on the woman’s pancreas to overcome the resistance to keep blood glucose normal. If her pancreas function is not optimal or she already has insulin resistance from before the pregnancy that is now increased, the blood glucose levels may rise to levels higher than normal.
What happens then? The extra, unabsorbed and unused glucose stays in the bloodstream instead of entering your cells – and this is a known risk factor that can lead to several significant complications for both mother and baby during pregnancy.
If you are diagnosed with gestational diabetes, your baby could be at risk of:
- Macrosomia: an excess of insulin production that leads to large birth weight
- Preterm birth: high blood sugar levels can lead to early labour
- Respiratory distress syndrome: when a baby requires help breathing or extra oxygen
- Hypoglycaemia: babies can develop sudden episodes of low blood sugar immediately after birth due to high insulin production
- Neonatal jaundice
- Type 2 diabetes: babies born to mothers with gestational diabetes are at higher risk of developing Type 2 diabetes later in life
“These risks for the baby are well known and well documented,” says Dr Pretorius, “but what people may not realise is that the mom is also at risk. We’ve seen that mothers who have developed gestational diabetes have a much higher chance of developing diabetes in the years after they’ve given birth. This is because they were always at risk – before pregnancy, during, and after. Their pancreas has failed the test of insulin resistance during the pregnancy and is very likely to fail again”.
Gestational diabetes is also linked to a heightened risk of developing high blood pressure and preeclampsia, a serious pregnancy-related complication that could put both mother and baby’s lives at risk during delivery.
If you are concerned about anything pregnancy or birth related, schedule an appointment with one of Mediclinic’s expert gynaecologists and obstetricians.
Mediclinic hospitals, day clinics and staff are ready to welcome you for your regular doctor’s appointments.