A person scheduled to have a blood sugar test should?

For a blood sugar test, particularly a fasting blood sugar test, it is essential for the individual to fast beforehand. Fasting usually means not consuming any food or beverages except water for a specified period, typically 8-12 hours prior to the test. This state helps in obtaining accurate measurements of blood glucose levels without the influence of recent dietary intake.

Drinking water, while generally acceptable during fasting, is not the primary requirement compared to the necessity of fasting. Similarly, consuming protein or carbohydrates can directly impact blood sugar levels, which is why they are not appropriate choices before the test. The goal is to assess the body's baseline glucose levels, which can only be accurately gauged if the person has not eaten for an adequate duration prior to testing. Thus, fasting is crucial to ensure that the results of the blood sugar test are valid and can be used effectively to evaluate the individual’s health status relative to blood glucose management.