Put simply: Elevated blood sugars often occur in pregnancy and are commonly caused by gestational diabetes (GDM). Mothers with Type 1 diabetes and Type 2 diabetes are also likely to have elevated sugars if pregnant. Around 1 in 5 pregnant women develop GDM.
The more complex story: In pregnancy there many hormonal changes that occur to the mother in order to facilitate the growth of a baby. Many of these changes are caused by hormones produced by the placenta. Some of these hormones cause the mother’s insulin receptors to become resistant to insulin. Insulin is a chemical, and when bound to the insulin receptor on a cell surface, allow for the movement of sugar from the blood into the cell.
If a person is insulin resistant, then they require more insulin to transport sugar (or glucose) out of the blood and into the cell. This is the same process that causes type 2 diabetes.
As the placenta grows in pregnancy, more and more hormones are made and released to support the growth of baby. At some point the mother may not be able to produce enough insulin to overcome the resistance, and if this occurs blood glucose levels rise.
High glucose levels readily cross the placenta and expose the baby to this diabetic state.
Who is at risk? Everyone is at risk and so it is recommended that all pregnant women are screened using a glucose tolerance blood test at 24-28 weeks’ gestation.
Certain women are at a much higher risk and should be screened before becoming pregnant, at 12 weeks’ gestation and again at 24-28 weeks if not previously diagnosed. High risk factors for gestational diabetes include
What are the symptoms of gestational diabetes? Usually there are no obvious symptoms. The only way to diagnose gestational diabetes is by having glucose tolerance blood tests.
How is gestational diabetes diagnosed? All mothers should be checked at 24-28 weeks by having a 2-hour glucose tolerance test. High risk individuals should also be tested either before becoming pregnant and at 12 weeks gestation unless the diagnosis has already been made.
The Glucose tolerance test is performed by presenting to a testing facility in a fasted state. A blood test is taken followed immediately by consuming a sugary drink (75g glucose). Further blood tests at 1 hour and 2 hours need to be taken and the person being tested should remain inactive during the testing process.
With what criteria is gestational diabetes diagnosed? An elevation in blood sugars is diagnostic at either the fasting, 1 hour or 2-hour test. You only need 1 test to be abnormal for a diagnosis.
|Fasting glucose||1 hour glucose||2 hour glucose|
|5.2 mmol/l or more||5.2 mmol/l or more 10.0 mmol/l or more 8.5 mmol/l or more||5.2 mmol/l or more 10.0 mmol/l or more 8.5 mmol/l or more|
|92 mg/dl or more||180 mg/dl or more||180 mg/dl or more|
If I have diabetes in pregnancy does that matter? Complications due to high blood sugars occur to both the mother and the baby. It is vital to maintain blood sugar levels as near normal as possible throughout the pregnancy to minimise complications.
Complications that can happen to the baby include being bigger at birth with the associated risks of a delivery from a large baby. Babies are also likely to be more immature and can have breathing difficulties after birth as well as experiencing very low blood sugar levels. In the long term a child exposed to high blood sugar levels during gestation is more likely to be overweight and develop diabetes once an adult.
Complications to the mother include a difficult delivery and a high chance of having a caesarean section. The mother is also more likely to have problems with blood pressure and in an extreme situation can develop life threatening seizures from a condition known as eclampsia.
Safely controlling sugars minimises the chance of this happening.
Will gestational diabetes resolve after delivery? Generally, most cases of gestational diabetes disappear after pregnancy. This however does need to be confirmed 6-10 weeks after delivery with another 2-hour glucose tolerance test.
50% of mothers with gestational diabetes will go on to develop type 2 diabetes later in life and this is more likely if the correct lifestyle changes are not undertaken. If a mother with previous gestational diabetes becomes pregnant again then the next pregnancy should always be considered high risk for subsequent diabetes and be tested for early in pregnancy.
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