Looked up "what can affect results of fasting glucose test"....
The Fasting Plasma Glucose Test - Understanding the Fasting Plasma Glucose Test
"What Can Affect Test Results?
Results may vary from lab to lab, or -- in the same lab -- from day to day. As a result, two abnormal results from tests taken on two different days are required to confirm a diagnosis.
Results may be lower if blood is drawn in the afternoon rather than in the morning. And a glucose level sometimes can be “falsely low” if too much time passes between when the blood is drawn and the lab processes the sample.
The results can also be affected by previous or current medical conditions or by personal habits, such as smoking and exercise. "
When i'm having lab work drawn that has to be fasting, I fast x 12 hrs, no water or anything until after the blood has been drawn.
