Typically yes, but not always. Fasting eight hours before drawing bloodwork for the basic metabolic panel is recommended but not always practical. For example, if the test is taken at the doctor's office or hospital without prior planning, fasting before the test may not be possible. Blood glucose levels—one of the seven tests in the panel—should be measured fasting. It is used to screen for diabetes and should be below 100 mg/dL in non-diabetics. Blood glucose levels can rise after eating and be as high as 140 mg/dL in people without diabetes.