2 hour Oral Glucose Tolerance Test | OGTT

2 hour 75-g Oral Glucose Tolerance Test, OGTT, GTT (plasma)

Units	Fasting	1 hour	2 hour
mg/dL	92	180	153
mmol/L	5.1	10	8.5

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It has been recommended that a 2-h 75-g OGTT be performed on all women at 24 to 28 weeks’ gestation not previously found to have overt diabetes or gestational diabetes mellitus (GDM) during early testing in their current pregnancy.

The test should be done in the morning after an overnight fast of 8 - 14 hours and after at least 3 days of unrestricted diet (>150 grams carbohydrates per day) and unlimited physical activity. The subject should remain seated and should not smoke throughout the test.

One or more of the values from a 75-g OGTT must be equaled or exceeded for the diagnosis of GDM.
A fasting plasma glucose > 7.0 mmol/L (126 mg/dl) is diagnostic of overt diabetes