What is Gestational Diabetes?
Diabetes is a medical condition where the body is unable to adequately regulate the amount of sugar in the bloodstream. In a normal individual, after consuming a meal, insulin is produced by the pancreas to regulate the blood sugar levels and store excess sugar for future energy requirements. In a person with diabetes, either the pancreas does not produce enough insulin or the insulin receptors are not able to respond to insulin in the manner that they should.
Gestational diabetes is a form of diabetes that occurs only during pregnancy. That is, if a woman develops diabetes during pregnancy but never had it before, she has gestational diabetes. Gestational diabetes is also known as gestational diabetesmellitus and affects about 2-14% of all pregnancies. It usually develops sometime during second trimester. Unlike regular diabetes, gestational diabetes usually resolves itself once the pregnancy is over.
What Causes Gestational Diabetes?
Gestational diabetes is believed to be caused by the hormones from the placenta that help the baby develop. What happens is that the hormones block the action of insulin resulting in a condition called "insulin resistance". This impairs the mother's ability to use insulin and she may require as much as three times the amount of insulin to regulate her blood sugar levels. If she is unable to produce enough insulin, her blood sugar levels will increase, causing a condition called hyperglycaemia - when there is too much sugar in the blood.
What are the Risk Factors for Developing Gestational Diabetes?
Gestational diabetes can affect any mother, regardless of whether she is considered high risk or not. But generally, women who have any of the following risk factors are more likely to develop gestational diabetes:
- history of gestational diabetes during a previous pregnancy
- strong family history of diabetes (i.e. father, mother or sibling with diabetes)
- South Asian, black Caribbean, or Middle Eastern descent (as they have a higher prevalence of diabetes)
- has sugar in her urine
- previously gave birth to a big baby - usually larger than 4kgs
- previously had an unexplained stillbirth
- previously gave birth to a baby with a birth defect
- high blood pressure
Symptoms of Gestational Diabetes
There aren't really any symptoms for gestational diabetes, but common signs to look out for are:
- increased thirst
- increased urination
- blurred vision
It can be difficult to determine if a pregnant woman has gestational diabetes from these symptoms alone as most pregnant women usually experienced increased urination during pregnancy due to the pressure of the baby on the bladder. Fatigue is also a common symptom during pregnancy and may be completely unrelated to gestational diabetes.
Testing for Gestational Diabetes
Doctors will generally monitor any mother who has a high risk of developing gestational diabetes however they will also keep a check for sugar in the urine for all pregnant women. Somewhere between the 24th to 28th week of pregnancy, a doctor will order an oral glucose tolerance test (OGTT) for mothers with a high risk for developing gestational diabetes. Mothers who have sugar present in the urine will also have to take theOGTT.
Although sugar in the urine may be suggestive of gestational diabetes, it is no longer considered a reliable method for detecting gestational diabetes. A mother may have gestational diabetes without having sugar in her urine.
Other signs that prompt a doctor to request an OGTT are an unusually large baby or the presence of excess amniotic fluid. Large babies may be suggestive of gestational diabetes but are not necessarily indicative of it. Excessive amniotic fluid in the uterus may be due to a birth defect or gestational diabetes. Usually a doctor will order a detailed scan of the baby to eliminate the possibility of a birth defect before suspecting gestational diabetes.
The Oral Glucose Tolerance Test
Before taking the test, a pregnant woman is required to fast from midnight of the day before. A sample of blood is taken the following morning before she is given a sweetened solution containing 75 grams of sugar to drink. An hour later, she will have another blood sample taken, followed by a third blood sample after another hour. During the entire test, she is not allowed to consume any food or drinks.
Her blood samples are then analysed to check the sugar content. Fasting blood sugar levels should be between 60-100 mg/dL (mg of sugar per dL of blood volume). The blood sample taken after the first hour should be less than 200 mg/dL. After the second hour, the blood sugar levels should be less than 140 mg/dL. If the results show a reading between 140-200 mg/dL, a woman is considered to have impaired glucose tolerance - otherwise referred to as "prediabetes". A blood sugar level greater than 200 mg/dL is indicative of gestational diabetes.
Treating Gestational Diabetes
Treatment for gestational diabetes involves:
- regularly testing blood sugar levels to ensure that it remains in the healthy range.
- eating a healthy diet, particularly controlling the amount of carbohydrates consumed as these will affect the blood sugar levels.
- getting regular, moderate exercise as recommended by the doctor.
- keeping a healthy weight.
- keeping records of diet, physical activity and blood sugar levels.
In some cases, extra insulin may be required to help a mother with gestational diabetes control her condition.
After the Delivery
Gestational diabetes usually resolves itself by about six weeks after the delivery of the baby. Nevertheless, mothers who had gestational diabetes are still required to test their blood sugar levels to ensure the condition has resolved itself.
It is also important for a mother with a previous history of gestational diabetes to be aware that she is now more likely to develop gestational diabetes again during a future pregnancy. It is advisable for her to test her blood sugar levels up to three months prior to getting pregnant again.
Since both mother and child are at higher risk of becoming obese and developing type 2 diabetes later in life, it is also important that they both take preventative measures through lifestyle changes to reduce their risk of developing either condition later in life.