Screening for gestational diabetes is usually done once in the late second trimester, typically between 24 and 28 weeks of pregnancy, with earlier testing if you are high risk or had gestational diabetes before.

Typical testing window

  • Most guidelines recommend a oneā€‘time screening between 24ā€“28 weeks of pregnancy for people without known risk factors.
  • This is when pregnancy hormones start to significantly affect how the body handles sugar, so tests are more likely to pick up gestational diabetes.

Early testing for highā€‘risk patients

You may be offered testing earlier in pregnancy (even at your first prenatal visit) if you:

  • Had gestational diabetes in a previous pregnancy.
  • Have risk factors such as overweight/obesity, older maternal age, strong family history of diabetes, or prior very large baby.

If those early tests are normal, screening is usually repeated again at 24ā€“28 weeks.

What the test usually looks like

  • The most common first test is a ā€œglucose challengeā€ or oral glucose tolerance test (OGTT), where you drink a sugary drink and have your blood checked afterward.
  • If that screening test is high, a longer diagnostic OGTT with more blood draws is done to confirm gestational diabetes.

When to ask your provider

  • If you are around 24 weeks pregnant and have not heard about the test yet, it is reasonable to ask your midwife or doctor when it will be scheduled.
  • If you notice sugar in your urine on routine tests or develop symptoms like unusual thirst, frequent urination, or fatigue, you should contact your provider rather than waiting for the routine screening visit.

TL;DR: They usually test for gestational diabetes between 24ā€“28 weeks, but you might be tested earlier if you have risk factors or had it in a previous pregnancy.