Normal Reference Range for Oral Glucose Tolerance Test (OGTT)

In daily life, pregnant women undergo routine prenatal examinations to monitor their baby’s healthy development in utero. Specific tests are scheduled at designated time points during pregnancy. So, what is the reference range for normal oral glucose tolerance test (OGTT) values?

Reference Range for Normal OGTT Values

Normal OGTT values are defined as follows: fasting plasma glucose < 5.1 mmol/L; 1-hour post-glucose load glucose < 10.0 mmol/L; and 2-hour post-glucose load glucose < 8.5 mmol/L. If any one of these values exceeds the corresponding threshold, gestational diabetes mellitus (GDM) can be diagnosed. Specifically, GDM is diagnosed when any one of the following criteria is met: fasting plasma glucose ≥ 5.1 mmol/L; 1-hour post-glucose load glucose ≥ 10.0 mmol/L; or 2-hour post-glucose load glucose ≥ 8.5 mmol/L.

When blood glucose levels are elevated but do not meet the diagnostic criteria for overt diabetes, initial management should focus on lifestyle interventions. This includes controlling total caloric intake, eating smaller, more frequent meals, prioritizing high-fiber foods, and engaging in appropriate physical activity suitable for pregnancy—all aimed at optimizing glycemic control. If glycemic targets are not achieved with lifestyle modifications alone, insulin therapy should be initiated promptly.

For pregnant women scheduled to undergo the OGTT, maintain a normal diet for the three days preceding the test. On the evening before the test, fast after 9:00 p.m.—no food or drink (except water) should be consumed thereafter. We hope this information is helpful!