What is gestational diabetes (GDM)?
Sugar (glucose) is the main energy source for your baby. The placenta produces a number of hormones that raise your blood sugar levels. In addition the placenta actively pulls sugar out of your blood stream to meet the pregnancy’s needs. These hormone levels will increase throughout your pregnancy. To avoid high blood sugar, your body responds by making more insulin to keep blood sugar levels normal.
In some situations, some women cannot make enough insulin to keep the blood sugar levels normal. Their glucose level becomes abnormally high and these women develop diabetes in pregnancy, also called gestational diabetes.
Gestational diabetes symptoms
Diabetes in pregnancy care
Who is at risk?
While the causes are not clear, there are some population groups who are at a higher risk than others. Risk factors for gestational diabetes include:
Past diagnosis of gestational diabetes
Past pregnancy with a large baby
Certain health conditions such as polycystic ovarian syndrome (PCOS)
Gestational diabetes test
A glucose tolerance test (GTT) is usually performed at around 28 weeks of pregnancy. Testing any earlier is not useful, as the condition will not be revealed while the placental hormones driving the mother’s blood sugar up are at a lower level.
While the GTT is the basis for testing, it is not a particularly convenient or effective test. Women need to fast overnight, drinking only water. Then three blood tests are taken, one while fasting followed by two more: one and two hours after drinking a glucose solution. There has been a recent change in the formulation to make it more palatable, but it is still not very pleasant.
The test is artificial. When a fasting woman has a large dose of neat glucose, the blood sugar levels may or may not remain normal.
This test has poor reproducibility. Someone who has an abnormal test result on one day may show better results if the test is repeated. As the test is unpleasant, we do not tend to repeat it, so the first test result remains the basis of the diagnosis.
If the test is positive, we need to determine what this means on a day-to-day basis.
What to do after being diagnosed?
To really understand what is happening on a daily basis, we turn to finger-prick blood testing of blood sugar levels throughout a normal day.
This is where the test results become more meaningful. You may have a diagnosis of gestational diabetes based on a GTT, but daily monitoring shows that the sugar levels are normal. If the daily levels are normal, then the initial diagnosis has little implication for your pregnancy.
That said, the initial diagnosis still matters, as it can be a marker of increased risk of developing diabetes later in life. Monitoring during your pregnancy is important, even with normal sugar levels, as the hormones that push the sugar levels higher continue to rise.
If on a daily basis the sugar levels are high, it is important to normalise them. We achieve this with a diabetic diet, regular exercise and, depending on the severity, insulin to control the levels. In these cases, we also provide careful monitoring and management of the baby.
Management and treatment: Gestational diabetes diet
A diabetic diet is low in fat, low in simple sugars and high in complex carbohydrates. You should avoid eating processed foods while focussing on a diet high in vegetables. Diabetes Australia is an excellent resource for more information about diet.
How Dr Chris Nichols can help you
Screening for gestational diabetes is a routine part of our antenatal care. If the diagnosis is confirmed, I will arrange the appropriate steps in managing the condition throughout your pregnancy.
While the management of your pregnancy may change a little, if gestational diabetes is well controlled, it will have very little, if any, influence on outcomes.