The three-hour glucose test is used to detect gestational diabetes. It’s usually given if you failed the one-hour glucose screening. It’s crucial to follow your doctor’s instructions before taking this test. It’s usually a fasting test, which means you have to stop eating a certain amount of time before the test is taken. However, check in with your doctor for their specific directions on taking the test. Suffice it to say, there’s no cheat to help you pass the test. You want accurate results so you and your doctor can create a plan to keep you and baby healthy.