The induced hyperglycemia test in pregnant women must normally be done between the 24th and 28th week of pregnancy and at any time when there is a high risk (presence of multiple clinical factors). There are two approaches to the test. First, the pregnant woman can undergo a simple screening test that does not require fasting (1 h glucose level post 50 g), then a 2-hour OGTT can be administered only to those women who had results between 7.8 and 11.0 mmol/L on the simple test. The other approach is to use only the OGTT in all pregnant women. Interpretation values vary slightly depending on the approach.
In the 2-step approach, a diagnosis of gestational diabetes is made when one or more results is abnormal: greater than or equal to 5.3 millimoles per litre of glucose at zero time (≥ 5.3 mmol/L), ≥ 10.6 mmol/L after 1 hour and ≥ 9.0 mmol/L after 2 hours.
For the OGTT in a single step (1 hour post 50 g test not used), a diagnosis of gestational diabetes is made when one or more results is abnormal: ≥ 5.1 mmol/L at zero time, ≥ 10.0 mmol/L after 1 hour and ≥ 8.5 mmol/L after 2 hours.