3 hour Oral Glucose Tolerance Test | OGTT

3 hour Oral Glucose Tolerance Test, OGTT, GTT (serum, plasma)

Units	Fasting	1 hour	2 hour	3 hour
mg/dL	95	180	155	140
mmol/L	5.3	10	8.6	7.8

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The 3 hour OGTT is a diagnostic test for gestational diabetes. It measures glucose concentrations over three hours  after a 100-g oral glucose load. The test is done in the morning after an overnight fast of between 8 and 14 hours, and after at least 3 days of unrestricted diet (≥150 g carbohydrate per day) and physical activity. The test is performed on women not previously found to have overt diabetes or gestational diabetes mellitus (GDM) during early testing in their current pregnancy

At least two or more values must be equaled or exceeded for a positive diagnosis. A fasting plasma glucose > 7.0 mmol/L (126 mg/dl) is diagnostic of overt diabetes

These values represent the equivalent glucose oxidase plasma values calculated from the original data using the Somogyi-Nelson technique [3-5].