Every so often I come across a discussion questioning the accuracy of a particular brand of blood glucose (BG) meter. Then things seem to get way out of hand, with regard to the assumptions made, and before you know it, that particular brand of meter is considered inaccurate and not recommended for use by those partaking in the discussion. However, albeit I acknowledge concerns and frustrations when you lose confidence in your meter, it is hardly appropriate to take information from a discussion board and make a decision as to whether your meter is accurate or not, so what should you do?
When a reading doesn’t make sense, I always refer back to the basics of diabetes health education, “When in doubt of readings: Review your technique and make sure the unit is being used properly, review storage and expiration date of strips, and use the control solution to verify the strips are working with the meter”. If then there are still results that come into question you should ask if the numbers are out of line with what the unit was designed to do? Blood glucose meters are approved by the FDA with an expected accuracy of plus or minus 20% of the actual reading 95% of the time for BG readings 75mg% or above, or plus or minus 15% for BG readings lower than 75mg%, and ALL blood glucose meters on the market today met that standard when reviewed and approved by FDA. What this means is that a BG reading of 100 can actually be 80 to 120, yet not out of a range in which a good clinical decision can be made by the person with diabetes (PWD). Another example is, if the reading is 200, then the actual BG value could be 160 to 240, and for a person with Type 2 diabetes, this one rreading would not lend towards any differing treatment or action. For PWDs with Type 1 diabetes it may be another matter, and immediate changes to a dose of insulin should be done with caution and perhaps another test to ensure precision, which by definition is the ability to duplicate results, which is different than accuracy. Accuracy is defined as the ability to get as close to the true reading as is possible. So I can be inaccurate but highly precise, kind of like my long-iron approaches from 200 yards, always left of the green but nowhere near the pin!
There are other factors totally unrelated to the brand of the meter and are reviewed in this excellent summary of the limitations of blood glucose meters.
The future of blood glucose monitoring: Worth noting is that there are new suggested standards, for which there is no hint by FDA they will adopt them, but a few of the meters don’t meet those new standards, referred to as ISO standards. ISO standards state that readings must be within plus or minus 15% at least 99% of the time, which lends towards fewer readings potentially outside of the range, which is also narrowed from plus or minus 20%.