Screening for Gestational Diabetes

The purpose of screening is early diagnosis and treatment. Screening tests are usually administered to people without current symptoms, but who may be at high risk for certain diseases or conditions.

Your doctor should assess your risk for gestational diabetes at your first prenatal visit. If you have a fasting blood sugar greater than 126 milligrams per deciliter (mg/dL) [7 mmol/L], or a random blood sugar greater than 200 mg/dL (11.1 mmol/L), that is confirmed on another day, you meet the criteria for the diagnosis of diabetes and you do not need to be screened.

If you are at high risk of developing gestational diabetes—very obese, prior history of gestational diabetes, prior delivery of a big baby, glucose in your urine, or a strong family history of diabetes—your doctor may recommend that you undergo glucose testing as soon as possible. If your initial test is not positive, you should be retested between 24 and 28 weeks of gestation.

Women who are of average risk should be given the 50-gram screening test between 24-28 weeks of gestation.

Newer guidelines do not require glucose testing for low-risk women, but to be low risk you must meet all of the following criteria: less than 25 years of age, normal weight before pregnancy, not a member of an ethnic group with a high risk of diabetes (Asian American, African American, Hispanic American, Native American or Pacific Islander), no known diabetes in any siblings or parents, no history of abnormal glucose tolerance, no glucose in urine, and no history of poor obstetric outcomes.

Screening Tests

50-gram glucose screening test—You do not need to fast before this test. You are given a drink that contains 50 grams of glucose. One hour later, your blood sugar level is tested.

If your blood sugar level is less than 130 mg/dL (7.2 mmol/L) at the one-hour mark, the likelihood that you have gestational diabetes is low, and you do not require further testing.

If your blood sugar level is greater than 130 mg/dL (7.2 mmol/L), the test is considered abnormal or positive. Your chance of having gestational diabetes mellitus is 90%. You will need to take the 3-hour oral glucose tolerance test to confirm the diagnosis. Not all women that have an abnormal or positive 50-gram glucose test have gestational diabetes.

References:

American Diabetes Association website. Available at: http://www.diabetes.org/home.jsp.

American Diabetes Association. Gestational diabetes mellitus: position statement. Diabetes Care. 2004;25(supple):S88-S90.

The National Institute of Child Health and Human Development website. Available at: http://www.nichd.nih.gov/.

Setji TL, Brown AJ, Feinglos MN. Gestational diabetes mellitus. Clinical Diabetes. 2005;23: 17-24.

Maresh M. Screening for gestational diabetes mellitus. Semin Fetal Neonatal Med. 2005;10:317-323



Last reviewed June 2008 by David Juan, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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