What are the normal values for the oral glucose tolerance test (OGTT) in pregnant women?

The purpose of the oral glucose tolerance test (OGTT) is to definitively diagnose gestational diabetes mellitus (GDM). Today, the incidence of GDM among pregnant women is increasing significantly; in severe cases, it may even endanger both maternal and fetal lives. Consequently, many pregnant women undergo OGTT during routine prenatal examinations. So, what are the normal reference values for OGTT in pregnancy? Below is a detailed explanation.

What Are the Normal OGTT Values for Pregnant Women?

The normal OGTT values for pregnant women are as follows: fasting blood glucose ≤5.1 mmol/L, 1-hour post-glucose load ≤10.0 mmol/L, and 2-hour post-glucose load ≤8.5 mmol/L. A diagnosis of gestational diabetes is established if any one of these three values meets or exceeds the corresponding threshold. In resource-limited settings, fasting plasma glucose is first measured between 24–28 weeks’ gestation. If fasting glucose exceeds 5.1 mmol/L, GDM can be diagnosed directly without performing the 75-g OGTT. If fasting glucose falls between 4.4–5.1 mmol/L, a 75-g OGTT should be performed as soon as possible. If fasting glucose is below 4.4 mmol/L, the 75-g OGTT may be deferred temporarily. However, for women with high-risk factors, even if the initial OGTT yields normal results, repeat testing in late pregnancy may be necessary. Should any value reach or exceed the diagnostic thresholds, prompt medical evaluation at a hospital is strongly recommended to minimize avoidable risks during delivery.

Additional Information: Important Considerations for OGTT

1. During the test, smoking, eating, and drinking water are prohibited. Light walking is permitted, but vigorous physical activity must be avoided. Pregnant women undergoing the test should remain calm and avoid emotional fluctuations due to repeated blood draws; full cooperation with healthcare personnel during each blood sampling is essential.

2. If symptoms such as pallor, nausea, or syncope occur during the test, the procedure must be discontinued immediately. If these symptoms arise 3–4 hours after glucose ingestion, reactive hypoglycemia should be suspected; blood glucose must be measured urgently, and the patient should be given food promptly.

The above outlines the normal OGTT reference values for pregnant women. We hope this information proves helpful to you.