During pregnancy, a glucose test is a routine screening that assesses how the body processes sugar. It helps healthcare providers monitor maternal and fetal well-being by providing important information about glucose management.
What is the Glucose Test?
The glucose test screens for gestational diabetes, a condition where the body cannot effectively regulate blood sugar during pregnancy. This screening is typically conducted between 24 and 28 weeks, though it may be done earlier if risk factors are present.
There are two main types: the 1-hour glucose challenge screening and the 3-hour oral glucose tolerance test. The 1-hour test is an initial screening where you drink a 50-gram glucose solution, and your blood sugar is checked an hour later. If the 1-hour screening result is elevated, a 3-hour oral glucose tolerance test is usually recommended to confirm a diagnosis. This diagnostic test involves fasting, a baseline blood draw, drinking a 100-gram glucose solution, and then multiple blood draws over three hours.
Preparing for an Accurate Result
Proper preparation helps ensure accurate test results. Maintaining a balanced diet in the days leading up to the test is recommended. This includes consuming a regular amount of carbohydrates, rather than restricting them. Foods like fruits, whole grains, lean meats, legumes, and non-starchy vegetables are beneficial choices.
Avoid excessive sugary foods, refined carbohydrates, and sugary drinks immediately before the 1-hour screening, as these can temporarily spike blood sugar levels. Strenuous physical activity should be avoided right before the test, particularly for the 3-hour test where remaining sedentary is often advised. Staying adequately hydrated by drinking plain water is also important. Discuss any medications you are taking with your healthcare provider, as some may affect test results.
On the Day of Your Test
Specific instructions for the test day vary depending on whether you are taking the 1-hour screening or the 3-hour diagnostic test. For the 1-hour glucose challenge test, fasting is typically not required. You can eat a normal meal beforehand, avoiding overly sugary foods. You will be given a sweetened liquid containing 50 grams of glucose to drink within about five minutes. Your blood will then be drawn approximately one hour after you finish the drink.
For the 3-hour oral glucose tolerance test, you will need to fast for at least 8 to 12 hours before the initial blood draw. Only sips of plain water are usually allowed during this fasting period and throughout the test. Upon arrival, a fasting blood sample will be taken, followed by drinking a 100-gram glucose solution. Afterward, blood samples will be collected at one, two, and three-hour intervals. It is generally advised to remain at the clinic or lab for the entire duration of the test, as activity can interfere with the results.
Understanding Test Outcomes
A “passing” result for the 1-hour glucose screening test generally means your blood sugar level is below 140 mg/dL one hour after drinking the glucose solution. If your blood sugar level is 140 mg/dL or higher, it indicates an elevated result, requiring further testing with the 3-hour oral glucose tolerance test. For the 3-hour test, specific blood sugar level thresholds are evaluated at fasting, one, two, and three-hour marks.
If two or more of the blood sugar levels during the 3-hour test are elevated, it typically leads to a diagnosis of gestational diabetes. If diagnosed, gestational diabetes is a manageable condition, often through dietary adjustments and regular moderate physical activity. Your healthcare provider will discuss appropriate steps to ensure the health of both you and your baby.