I’m sure it will ruin your day to learn that for the FDA to consider a test strip accurate it must be within 20% of correct. That means if your blood sugar is really 100, any test strip that reads from 80 to 120 is considered accurate and can be approved.
How far off will your meter be if calibrated wrong? Depends on the meter. I’ve seen cases of 100 or 150 points off. If I find a patient’s meter mis-calibrated I don’t even look at the numbers or the log. They are too likely to be wrong.
Find out more about this book:The Born-Again Diabetic: The handbook to help you get your diabetes in control (again)