Improper testing techniques comes to mind - not cleaning test area, uncalibrated
test equipment, etc. To be certain of your
blood sugar levels get an A1c [HbA1c, HgbA1c]
test.
An A1c test will inform you of your blood sugars levels for the past 2-3 months, the lifespan of new red blood cells. Excess blood sugars attach to new RBC's never getting absorbed for use as energy. The A1c captures this. It is the standard most doctors use to verify diabetes or not.