Gestational diabetes does not always give rise to symptoms and all pregnant women are therefore routinely screened to check their blood sugar levels during pregnancy. Gestational diabetes is typically characterized by a high blood sugar level (hyperglycemia) and relative insulin resistance.
The tests performed to check for and diagnose gestational diabetes include:
- Pregnant women are checked for impaired glucose tolerance, pre-diabetes or frank gestational diabetes as part of their antenatal screening, usually between the 24th and 28th week of gestation.
- Women at high risk of gestational diabetes include those with a family history or personal history of diabetes, gestational diabetes, or other conditions such as polycystic ovarian syndrome or acanthosis nigricans.
- Fasting blood sugar – Blood sugar levels are tested using a simple blood test after a person has fasted for around eight hours, usually overnight. A patient is considered to have gestational diabetes if the result is 126 mg/dL or more.
- Post prandial blood sugar – If the fasting blood sugar is raised, the blood sugar level is measured again two hours after a meal is eaten. Gestational diabetes is indicated if the 2- hour postprandial blood glucose level is 200 mg/dL or more.
- Urine glucose is also tested. Women with gestational diabetes have high glucose levels in their urine (glucosuria).
- An oral glucose tolerance test is also performed to confirm gestational diabetes.
- The health of the unborn baby is checked using ultrasonography, which may reveal macrosomia or large size of the baby for its gestational age.
Reviewed by Sally Robertson, BSc