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Glucometers and Clinically Approved Precision

Nina Ghamrawi, MS, RD, CDE
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Have you been seeing a range in readings? If you've seen your glucose range from 100 to 180 in a span of minutes, it's likely that you got a reading that was in error. While it's always best to double and triple check, all meters will typically have a range of 15-30 points depending on how high the true value is. This range, sadly, is still clinically approved. Take the average of the readings, if you're curious, and that will get you closer to the lab value.

What is the FDA Approved Range of Error?

On all meters, there's a level of precision that needs to exist for the meter to be clinically approved by the FDA. Clinically speaking, all meters are FDA approved if their range is within 15% of the lab value. The lab blood draw is labeled as a golden standard that all meters are compared to.

So if the lab measures your glucose at 150, any given meter can range 15%, or 22 points above or below (128-172) and still be considered accurate.

Sounds confusing? Well, that's because it is. The reason that the FDA has this wide acceptable range is because glucometers are measuring capillary blood, which can vary from the "golden standard" lab value.  

Just How Accurate is My Meter?

The FDA also approves for all meters that 95% of all readings must be within that range. Which translates to mean that 5% of all readings on any given meter can be outside of that range and is still considered acceptable.

How Different Meters Compare:

The Diabetes Technology Society (DTS) recently revealed long-awaited results from its Blood Glucose Monitor System (BGMS) Surveillance Program. The rigorous study tested the accuracy of 18 popular blood glucose meters (BGM) used in the US. These FDA-cleared meters were purchased through retail outlets and tested rigorously at three study sites in over 1,000 people (including 840 people with diabetes). The results were troubling: only six out of the 18 devices met the DTS passing standard for meter accuracy – within 15% or 15 mg/dl of the laboratory value in over 95% of trials.

The results:

The devices that passed were:

The devices that failed were:  

(see the full results of the glucose meter comparison study here)

So if you are looking for a meter, definitely go with one that passes this test. Be careful, because not all of these may be covered on your insurance's formulary. It is best to ask your insurance plan carrier about what meters and supplies are covered.

As always, the best thing you could do when testing your glucose with this method is to use the same meter to get consistent readings. If you are taking insulin, you will learn how to titrate the insulin according to the readings and your symptoms. But if you switch between different meter brands, your insulin titration approach may need to also change. Consult your doctor or CDE regarding insulin titration changes if you decide to switch meters.