Diabetes in Pregnancy

Diabetes is a common medical condition in pregnancy and affects approximately 1 in 6 pregnancies. Diabetes is associated with serious potential problems. Diabetes is potentially dangerous in pregnancy and is a High Risk Factor. Diabetes needs to be diagnosed early, monitored closely and treated appropriately.

Diabetes can be pre-existing or it may develop for the first time in pregnancy.

Pre existing diabetes can be associated with genetic abnormalities.

Gestational diabetes (GDM) can result in epigenetic activation of certain genes that may set the baby on a life long road of obesity and predisposition to diabetes later in life. Diabetes has potentially serious effects on fetal well being in utero and needs to be monitored and treated closely.

Reduce the risk

Fortunately few pregnant women have pre existing diabetes. They must be informed to try and get their diabetes well controlled before falling pregnant. Pre pregnancy counselling and involvement of their endocrinologist is essential.

Most women who develop diabetes do so during pregnancy (GDM).

It is therefore important to inform all women of the potential to develop diabetes in pregnancy. It is also wise to inform patients in advance about the benefits of appropriate weight gain in pregnancy and to give patients dietary advice.

It is recognised that a family history of diabetes, obesity, excessive weight gain in pregnancy as well as other conditions such as polycystic ovarian syndrome (PCOS) will increase the risk of a mother developing GDM.

It is important to acknowledge that GDM will almost always disappear after delivery of the baby. It is however also important that patients are aware that it is associated with a 50% chance of developing maturity onset diabetes later in life.

Diabetes can be a pre existing medical condition (Type 1) and in these cases it is essential to try and stabilise the diabetes as much as possible prior to conception.

Poorly controlled Type 1 diabetes in pregnancy can be associated with fetal anomalies (cardiac, renal & sacral agenesis). These women are usually already on insulin treatment and they will need to have joint care between the obstetrician and the endocrinologist as their insulin requirements through pregnancy will change and will require close supervision.

Fortunately most cases of diabetes develop during pregnancy (Gestational Diabetes GDM). This develops during the pregnancy and can have serious potential effects on the pregnancy but does not usually cause any malformations.

Diabetes in pregnancy will require close monitoring.

Diagnosis and management

GDM is diagnosed under new criteria by performing a glucose tolerance test (GTT) ADIPS criteria.

Once a diagnosis of GDM is made patients will be referred to a Diabetes Educator who will instruct them on dietary issues and weight gain.

Patients will also be instructed in monitoring their blood sugar levels – (fasting and 2 hours after meals). Fasting blood sugar levels must be kept below 5mm/l and post prandial blood sugars between 3.5 and 6.5 mm/l. Patients will also need to perform regular fetal heart monitoring tests by having CTG’s.

I understand that it is a hassle to do all of this but it is necessary because diabetes can have serious effects on the fetus.

Why does diabetes cause trouble in pregnancy

High blood sugars crossing the placenta will induce the fetus to increase its insulin production. Fetal blood sugars will be normal but this can only be achieved by the fetus increasing its blood insulin level (hyperinsulinaemia). When maternal blood sugars fall between meals or during the night, the fetal blood sugars will drop precipitously because of the elevated blood insulin levels. This could make the fetus potentially hypoglycaemic.

Exposure to high blood sugars in utero may result in activation of certain genes (epigenetic determination) and can commit a fetus to an adult life of obesity and potential predisposition to diabetes later in life.

High fetal insulin blood levels stimulate the release of Growth hormone and the fetus grows rapidly as a result. Certain organs such as the fetal heart can enlarge too much. The cardiac septum that separates the left and right sides of the heart can impede fetal cardiac blood flow. More than this a large fetus can cause obstructed labour and increase the chances of a Caesarean Section.

The placenta also grows rapidly. This is called hyperplacentosis and is associated with a number of other risks.

A large placenta may extend into the lower uterine segment and this can increase the risk of antepartum haemorrhage (APH).

A large placenta is associated with Polyhydramnios (too much liquor) which can result in a malpresentation, premature rupture of membranes and premature labour.

For complex immunological reasons a large placenta will also increase the risks of developing pre eclampsia.

It is clear that diabetes is a high-risk condition in pregnancy and needs to be well controlled. It often requires combined care from the Obstetrician, the diabetes educator and the endocrinologist. It is necessary to control weight, diet and blood sugars and monitor fetal growth with regular ultrasound scanning and fetal heart monitoring CTG’s. Diabetes must be well controlled.

If maternal blood sugars remain elevated despite dietary changes then it will be necessary to be commenced on insulin. These patients will always be under the care of an endocrinologist. They commonly need to be induced earlier because of the potential harmful effects of diabetes.

Fortunately most women with GDM will have well-controlled blood sugars and they will have reduced risks and healthy babies.