Postpartum 75-Gram Glucose Tolerance

Test ID: 


CPT code:

82951, 82952 (x2)


•Glucose Tolerance, Gestational Diabetes (Fasting, One-hour, Two-hour, and Three-hour)

Clinical Use:

Diagnose gestational diabetes

Specimen Type:

Serum or plasma

Additional Information:

In 2013,2 the American College of Obstetricians and Gynecologists (ACOG) recommended that all pregnant women be screened for gestational diabetes mellitus (GDM)—whether by patient history, clinical risk factors, or with a 50-gram, one-hour loading test at 24 to 28 weeks of gestation to determine blood glucose levels—and suggested relying on the result of the 100-gram, three-hour oral glucose tolerance test for diagnosis (often referred to as a “two-step” method).

The American Diabetes Association (ADA)1 released standards that vary from the ACOG recommendations. The ADA standards recommend a simplified “one-step” approach to the screen and diagnosis of gestational diabetes mellitus with a 75-gram, two-hour glucose tolerance test. The test according to the ADA recommendations is Gestational Glucose Tolerance Screening and Diagnostics Test (Two-hour, ADA Recommendations) 

Requested Volume: 

1 mL serum or plasma each tube

Minimum Volume: 

0.5 mL serum or plasma each tube

Container Type: 

Gel-barrier tubes (4) or gray-top (sodium fluoride/potassium oxalate plasma) tubes (4)


Draw a fasting blood sugar before administering 100-gram glucose, and draw blood at one, two, and three hours. The subject should remain seated and not smoke throughout the test. Submit 1 mL serum or plasma for fasting, one-hour, two-hour, and three-hour specimens. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label each tube with patient’s name and collection time interval (ie, fasting, one-hour, two-hour, and three-hour).

Storage Instructions:

Maintain specimen at room temperature.

Rejection Criteria:

Frozen gray-top tube (frozen plasma from gray-top is acceptable); stressed patient (surgery, infection, corticosteroids) should not have GTT; specimens not labeled with collection time intervals (i.e., fasting, one-hour, two-hour, and three-hour)

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MCI Diagnostic

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Mon – Sat: 7AM-11PM

Sun: 7AM-3PM

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