Gestational diabetes is a type of diabetes that affects women during pregnancy. Diabetes is a condition where there is too much glucose (sugar) in the blood.

Normally, the amount of glucose in the blood is controlled by a hormone called insulin.

However, during pregnancy, some women develop higher than normal levels of glucose in their blood, which insulin can't bring under control.

Gestational diabetes usually develops in the third trimester (after 28 weeks) and usually disappears after the baby is born. However, women who develop gestational diabetes are more likely to develop type 2 diabetes later in life.

Types of diabetes

Gestational diabetes is first diagnosed during pregnancy. The two other main types of diabetes are:

• type 1 diabetes – when the body produces no insulin at all (often referred to as juvenile diabetes or early-onset diabetes)
• type 2 diabetes – when the body doesn't produce enough insulin and/or the body’s cells don't react to insulin (insulin resistance)

Symptoms of gestational diabetes

Gestational diabetes often doesn't cause any symptoms. This means you may be screened for the condition at your first antenatal appointment by a venous glucose sample, at around weeks 8-12 of pregnancy.

If you are at increased risk of gestational diabetes you will be offered a full test, which takes place during weeks 24-28 of pregnancy.

Read more about how gestational diabetes is diagnosed.

High blood glucose (hyperglycaemia) can cause some symptoms, including:

• a dry mouth with increased thirst
• needing to urinate frequently, especially at night
• tiredness
• recurrent infections, such as thrush (a yeast infection)
• blurred vision

Read more information about hyperglycaemia.

How common is gestational diabetes?

Gestational diabetes is a common condition, and up to 18 in every 100 women giving birth in England and Wales may be affected.

Treating gestational diabetes

Gestational diabetes can be controlled with diet and exercise. However, some women will need medication to keep their blood glucose levels under control.

Read more about how gestational diabetes is treated.

If gestational diabetes is not detected and treated, it can increase the risk of birth complications for both the mother and baby.

Read about the complications of gestational diabetes.