Fasting is an essential requirement before the diabetes test, which means that you should refrain from eating anything for at least 8-12 hours. If you are on some medication, consult your doctor before the test as medications could impact the results. Although, you can drink as much water as you like before the test to keep yourself hydrated. In addition to that, you should avoid exercising a lot, eating oily or spicy foods, taking stress, and not taking enough rest.