Causes of Gestational Diabetes

Gestational diabetes (GD) is a form of diabetes that specifically develops during pregnancy. Gestational diabetes occurs following the body becoming resistant to the effects of insulin.

There are a number of causes of gestational diabetes with the effect of placental hormones being one of the most significant causes.

Gestational diabetes usually subsides after pregnancy but can sometimes remain as type 2 diabetes.

Risk factors for gestational diabetes

The following factors are known to increase the risk of developing gestational diabetes:

• Having previously had gestational diabetes in a prior pregnancy
• Having a BMI over 30
• Having had a large baby weighing 4.5kg (10lbs) or more
• Having a close family member that has type 2 diabetes or has had gestational diabetes
• Being of South Asian, African Caribbean or Middle Eastern origin

Placental hormones

During pregnancy the body produces high levels of a number of the following hormones:

• Human placental lactogen (hPL)
• human placental growth hormone (hPGH)
• Oestrogen
• Progesterone

These hormones, and HPL in particular, reduce the effectiveness of insulin.

As your baby grows, a higher level of these hormones are needed and, as a result, the further into your pregnancy you are the higher the likelihood of developing insulin resistance and gestational diabetes.

Human placental lactogen (hPL) and human placental growth hormone (hPGH)

These hormones are produced by the placenta during pregnancy and assist with feeding and growth of the baby. During pregnancy, levels of these hormones increase significantly, with hPL increasing by up to 30 times and hPGH increasing by up to 8 times.

Research indicates that both of these hormones can lead to increased, and even severe, insulin resistance.

Gestational diabetes and type 2 diabetes

Gestational diabetes and type 2 diabetes are closely linked and women that develop gestational diabetes will usually have insulin resistance to some extent before their pregnancy.

As a result, the factors that are known to cause type 2 diabetes also contribute to the development of gestational diabetes.
Having a significant amount of visceral fat growing around main organs such as the liver, pancreas and digestive organs can cause insulin resistance and therefore contributes to the development of insulin resistance.

A build up of visceral fat is more likely to occur if you have a BMI value over 30.