Gestational Diabetes Mellitus – Part 1

What Is Gestational Diabetes?

Gestational diabetes mellitus is a type of diabetes that occurs during pregnancy. It usually goes away after the baby is delivered. Approximate 10 to 15% of women will develop gestational diabetes during pregnancy. Gestational diabetes happens in the late second or early third trimester of pregnancy – usually after 24 weeks.

Diabetes mellitus is a condition in which the cells in the body are unable to effectively obtain glucose (sugar) from the bloodstream. Glucose is needed to provide the body with energy for day-to-day activities.

The pancreas produces a hormone known as insulin that moves glucose from the bloodstream into the body’s cells, where it can be used for energy. When the movement of glucose into the cells is delayed, blood glucose levels increase, causing diabetes to happen.

Two possible reasons can result in delayed movement of glucose into the cells:

  • Reduced insulin production from the pancreas
  • Resistance to the effects of insulin at the cells

Why Does Gestational Diabetes Happen?

During pregnancy, the placenta (the blood source for the baby) produces hormones which help the baby grow and develop. The levels of these hormones increase as pregnancy progresses. Some of these hormones
cause insulin resistance and block the action of the mother’s insulin. In order to keep blood glucose levels normal, a mother’s pancreas needs to make 2 to 3 times the normal amount of insulin due to this insulin resistance.

If the mother’s pancreas is unable to produce the extra insulin or if her body becomes more insulin resistant, gestational diabetes develops.

When the baby is born, the need for extra insulin falls. Blood glucose levels will usually return to normal and gestational diabetes disappears.

Which Woman Is At Risk Of Developing Gestational Diabetes?

  • Older in age, especially if over 40 years of age
  • Has first degree relative with type 2 diabetes mellitus
  • Overweight or obese (body mass index >25 kg/m2)
  • Had gestational diabetes in a previous pregnancy
  • Had a large baby (weighing more than 4.0 kg) or obstetric complications
  • Known history of polycystic ovary syndrome (PCOS)

How Is Gestational Diabetes Diagnosed?

Gestational diabetes is diagnosed via blood tests – the Oral Glucose Tolerance Test (OGTT).

After fasting for 8 to 12 hours, a blood sample is taken to check blood glucose level. The woman will then have a drink containing 75 grams of glucose. Blood samples for glucose are taken one hour and two hours later.

If blood glucose level is above a certain value at fasting, one or two hour test, the woman has gestational diabetes.