Gestational Diabetes Mellitus

Gestational DiabetesGestational Diabetes Mellitus (GDM)

This usually develops during the 2nd trimester (usually from around weeks 24-28), but if found in the first trimester, this is usually because diabetes was un-diagnosed prior to pregnancy.

It can affect up to 4% of pregnancies and Gestational Diabetes usually arises because of lack of insulin to meet the extra needs of the pregnancy.

It is a manageable condition, where you will be referred to a dietitian who will advise you about what foods you should and shouldn’t eat to keep your blood sugars in check.  If they can not be controlled then you may need to take tablets or insulin injections to treat the diabetes.

Usually Gestational Diabetes will go after the baby is born, but you are more likely to get it with subsequent pregnancies and there is a 30% chance that you will develop Type 2 Diabetes later in life (general population is 10%).

Diagnosis is with a Oral Glucose Tolerance Test (OGTT), where it involves a blood test prior to breakfast after having fasted between 8 – 12 hours, then again 2 hours after a sweet glucose drink, to measure your blood glucose levels.

The results of a OGTT:

For people without diabetes: 

  • Fasting – Under 6mmol/L
  • After 2 Hours – Under 7.8mmol/L

People with Impaired Glucose Tolerance (IGT):

  • Fasting – 6.0mmol/L to 7.0mmol/L
  • After 2 hours – 7.9mmol/L – 11.0mmol/L

Diabetic levels:

  • Fasting – Over 7.0mmol/L
  • After 2 hours – over 11.0mmol/L

Symptoms of Gestational Diabetes:

Normally you will not notice any symptoms with gestational diabetes, this is why you will have a routine check at around 24-28 weeks of your pregnancy.  But occasionally you may notice some of the following:-

  • Increased thirst
  • Urinating more than normal
  • Increased tiredness

But these symptoms are also associated with pregnancy and will most probably not be caused by GDM, but if you notice them, please tell your Dr or Midwife, so they can arrange for you to be checked.

Complications of Gestational Diabetes:

When Gestational Diabetes is uncontrolled it can lead to the following:

  • Pre-Eclampsia
  • Premature labour – prior to 37 weeks
  • Increased baby weight – as the higher blood sugar levels may make the baby put on extra weight – which could make labour and birth more difficult or increase the chances of a Caesarean.

Causes of Gestational Diabetes:

  • Being overweight or obese increases your chances of GDM
  • Previously had GDM in other pregnancies
  • Family history of Diabetes
  • Have Polycystic Ovary Syndrome (PCOS)
  • Previously had a large baby over 4.5kg/9lb 15oz