Two-hour glucose tolerance test: what to know

The test usually begins with a blood sample, followed by a glucose drink. You then wait at the clinic while your body processes it, with a later sample taken at the scheduled time. In pregnancy, the test may help assess gestational diabetes when screening indicates it is needed. The laboratory compares the results with the thresholds used by your service. A result outside the expected range does not by itself explain how you feel; your maternity or diabetes team will discuss what it means and whether further monitoring is needed.

Follow the clinic's instructions about fasting, usual meals, medicines, and arrival time because preparation can affect the result. Bring water if permitted and something to eat for after the final sample. During the waiting period, remain on site, avoid strenuous activity, and tell staff if you feel nauseated, shaky, sweaty, faint, or unwell. Ask in advance whether regular medicines should be taken before the appointment. An antenatal care package may include related monitoring and follow-up.

Tell the staff immediately if you feel faint, confused, unusually weak, or unable to keep the drink down. After leaving, contact your maternity team for persistent vomiting, severe weakness, or concerning symptoms such as reduced fetal movement. A glucose tolerance test is a planned assessment; urgent symptoms should be managed according to clinical advice rather than waiting for the result.

Ask whether you need to fast, which medicines to take, how long you will remain at the clinic, when results will be available, and what follow-up follows an abnormal result.