Gestational Diabetes

When a pregnant woman develops diabetes late in pregnancy usually after 28 weeks of gestation, it is called GDM or gestational diabetes mellitus.

The reasons for the pregnant lady developing GDM are multi – fold.


They usually have one or more risk factors such as south –Asian ethnicity, obesity, lack of physical activity, family history of diabetes, history of polycystic ovarian disease. The pregnant woman in addition might be elderly (over the age of 40), be pregnant with twins, which makes them more prone to developing this condition.

All pregnant women are screened with a fasting glucose value at the beginning of their pregnancy. Majority will have, what is called an OGTT or a oral glucose tolerance test at 28 weeks. In women who are high risk this test can be done earlier (20 or 24 weeks) and repeated at 28 weeks if negative. The OGTT involves fasting overnight, taking a glucose load of 75 mg usually and measuring the glucose levels at 0,1 and 2 hours.

Women who have GDM are treated very similar to woman with diabetes. Diet control, Oral hypoglycaemic agents and insulin are all options available. However there is a huge shift towards using insulin as the first line. Frequent monitoring of blood glucose levels are paramount for good obstetric outcomes.

Preterm labour, sudden fetal death, instrumental deliveries and caesarean sections are common in women with GDM. Babies of mothers with GDM are large and overweight and this is called macrosomia. Because of this normal delivery becomes difficult and shoulder dystocia is common. Shoulder dystocia is a condition wherein the shoulder of the baby gets stuck during delivery causing significant trauma to the mother and baby.

GDM usually resolves in the postpartum period and the mother’s blood glucose levels return to normal within 6 weeks. However majority of these women who had GDM in pregnancy will go on to develop diabetes in later life. They therefore need their blood glucose levels monitored on a yearly basis and have to successfully adopt lifestyle modification practices such as exercising regularly and eating a healthy diet. It is believed that babies of mothers with GDM are also at high risk of developing diabetes later on in life.


Dr. Vaishnavy Laxman
Consultant Gynaecologist
Kauvery Hospital, Chennai