The drink is to check to see if you have gestational diabetes. You will drink a small drink that taste like flat soda at your drs office. Then they will draw your blood and test it. If you fail to test they will have you take another one to verify. if you pass and there is no concern of diabetes you won't have to take a second test. Just follow your drs instructions and you will do great :) some drs have you fast before the test for a short time, some will tell you not to eat sweets for a certain period of time before the test. For example I was advised not to have sweets 72hrs before testing and to fast 1-3 before taking the test. You can call your drs office for help if they didn't give you instructions or if you lost them. Everyone takes the glucose test it's over before you know it :)