During pregnancy, a woman who previously did not have diabetes may develop diabetes due to various hormonal changes in the body. This is known as ‘Diabetes of Pregnancy’ or Gestational Diabetes. This type of diabetes usually develops after the first twelve weeks (first trimester) of pregnancy.
There are numerous complex reasons as to why diabetes may develop during pregnancy. Glucose (sugar) levels in the body are normally controlled within tight limits by the hormone insulin, produced in the body by the pancreas gland. Pregnancy hormones make glucose handling more difficult, the body becomes more resistant to insulin and the pancreas has to produce more insulin to keep up. If the pancreas has insufficient reserves to keep up - gestational diabetes develops.
Women routinely have blood tests requested at booking and at 28 weeks of the pregnancy. These tests include blood glucose levels. If the blood glucose levels are higher than they should be at either of these times – your healthcare professional will request a glucose tolerance test, to confirm the diagnosis of gestational diabetes.
When pregnant women see their midwife or doctor a routine urine test is requested. This may show the presence of glucose in the urine. This can be entirely normal and does not prove a diagnosis of diabetes. If your healthcare professional is suspicious of diabetes a glucose tolerance test is required to confirm the diagnosis.
It is a blood test. You are required to fast overnight, a blood test is then taken for glucose levels. You are then immediately given a standardized drink of sugar, followed by a blood test 2 hours later. The results take a few days to come through. A hospital nurse or midwife will contact you if the result is abnormal.
Gestational diabetes usually does not cause many symptoms and is usually not harmful. There may be an increased tendency to develop high blood pressure during the pregnancy. High blood sugars during pregnancy can lead to an increase in the size of your baby, which in turn may make a ‘normal’ delivery more difficult. If you have a big baby, you are also more likely to have a Caesarian section . These problems will be addressed by your obstetrician.
It is thought that gestational diabetes poses a lower risk to your baby than if you had diabetes before pregnancy. This is because gestational diabetes often develops after the first trimester of pregnancy (the first twelve weeks) during which many of the vital organs are formed.
Recent data from an Australian study showed a higher rate of miscarriages in women with gestational diabetes.
Gestational diabetes can however result in a large baby, which may lead to difficulties in labour, or even premature labour.
There is a very small risk of unexplained late still birth, because of this your healthcare team will tend not to let you continue your pregnancy much beyond your due date. This may mean you will have to be induced – i.e. have labour commenced artificially.
Your baby may also be at increased risk of developing low blood sugar (hypoglycaemia) low blood sugar after birth. This is due to the baby’s pancreas producing more insulin in response to high blood sugar levels in the placenta. You will be encouraged to feed baby (breast or bottle) as soon as possible after birth to reduce this risk.
If anyone in your immediate family has type 2 diabetes, or if you are overweight, your risk of gestational diabetes is higher. If you have had a previous stillborn child or if you have had a very large baby your chances of developing diabetes in pregnancy are increased. If you were diagnosed in a previous pregnancy you will be checked early in your future pregnancies - as it is likely to recur. Women over the age of 35 years may also carry a higher risk.
It is considered important to maintain normal blood glucose levels during pregnancy. This may be possible by diet alone. If sugar levels do not respond to diet, insulin is required. You will be taught how to monitor your blood glucose (sugar) levels at home using a small machine.
A third of women with gestational diabetes will require insulin. Diabetic tablets cannot be given during pregnancy.
Yes, often diabetes which develops during pregnancy goes away as soon as the baby is born. Blood sugar levels return to normal, dietary restrictions and insulin injections are no longer needed.
A repeat glucose tolerance test is usually arranged six weeks after delivery, to confirm blood glucose handling has returned to normal.
If you have had gestational diabetes, your risk of developing type 2 diabetes in later life is substantially higher. It is important to keep physically active and maintain a normal body weight as you age, to minimize your chances of developing type 2 diabetes.
Yes it is likely you may develop diabetes in future pregnancies as well.
If you are overweight, reducing weight may lower your risk of developing gestational diabetes. This will also help reduce your lifetime risk of developing type 2 diabetes.
Dr Nishan Wijenaike MD, FRCP
Consultant Physician (Diabetes and Endocrinology)
West Suffolk Hospitals NHS Trust
Bury St Edmunds