Confirmatory Test for Gestational Diabetes:
The 3 hour Oral Glucose Tolerance Test
Values > 140 mg/dl and <180 on the 1 hour oral glucose tolerance test require follow-up with a 3-hour
100 gram oral glucose tolerance test (OGTT)
If the patient has a screening value > 180 mg/dl, a fasting blood
sugar should be checked. An elevated fasting value of > 95 and screening test
> 180 mg/dl provides two abnormal values, and treatment for gestational diabetes is recommended.
3-hour 100 Gram Oral Glucose Tolerance Test (OGTT)
The 3 hour OGTT is done after an overnight fast for at least 8
hours but
not more than 14 hours after at least three days of unrestricted diet and
physical activity.
Abnormal 3-hour 100 gram OGTT values are:
- Fasting > 95 mg/dl
- One hour> 180 mg/dl
- Two hour > 155 mg/dl
- Three hour > 140 mg/dl
At least two out of four values must be equaled or exceeded to diagnose
gestational diabetes.
If only one value is elevated then
- Manage with diet and exercise.
- Consider retesting at 32 to 34 weeks for patients with risk factors.
REFERENCE:
*Guidelines for Care, California Diabetes and
Pregnancy Program,2002
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