Normal blood values for a 75 gram OGTT used to check for type 2 diabetes in those who are not pregnant: Fasting: 60 to 100 mg/dL (3.3 to 5.5 mmol/L) 1 hour: less than 200 mg/dL (11.1 mmol/L) 2 hours: less than 140 mg/dL (7.8 mmol/L)
How the Test is Performed
The most common glucose tolerance test is the oral glucose tolerance test (OGTT).
Before the test begins, a sample of blood will be taken.
You will then be asked to drink a liquid containing a certain amount of glucose (usually 75 grams). Your blood will be taken again every 30 to 60 minutes after you drink the solution.
The test may take up to 3 hours.