The Sweet Success Program of California recommends that all pregnant women be screened for gestational diabetes at 24-28 weeks, or earlier if risk factors are present. Screening is usually done using the 1 hour oral glucose tolerance test.

Patients should be screened at their first prenatal visit if any of the following risk factors are present:

• Family history of diabetes in first-degree relatives
• Previous history of:
  • Gestational diabetes
  • Macrosomia
  • Unexplained stillbirth
  • Malformed infant
• >25 years of age
• BMI >30
• Glucosuria > 2+
• Member of an ethnic/racial group with a high prevalence of diabetes (i.e., Hispanic-American, Native American, Asian-American, African-American, Pacific Islander, or of Indigenous Australian ancestry)
• Taking medications causing hyperglycemia (i.e. terbutaline,prednisone)

A plasma concentration >200 mg/dl (11.1 mmol/l) under any conditions outside of the context of a formal glucose challenge test or a fasting plasma glucose concentration  >126 mg/dl (7.0 mmol/l) warrants confirmatory testing as quickly as possible.

1 hour Oral Glucose Tolerance Test (OGTT)
The test can be done at any time of the day. Fasting is not required.
Administer a 50 gram glucose load followed by a one-hour plasma glucose:

• Negative test if : < 140 mg/dl
• Positive test if: > 140 mg/dl
  




• Values 140 mg/dl to 179 mg/dl require follow-up with a 3-hour 100 gram oral glucose tolerance test (OGTT) within one week.
• If the patient has a screening value > 180 mg/dl, a fasting blood sugar should be checked as soon as possible.

• An elevated fasting value of > 95 and screening test > 180 mg/dl provides two abnormal values, and treatment for gestational diabetes is recommended.
• If the fasting value is less than 95 then proceed with the 3 hour OGTT.

Women who were evaluated early during their pregnancy and found to be normoglycemic should have screening repeated at 24 to 28 weeks.