How Accurate Do Our Blood Glucose Meters Have To Be?

Patient Expert

The U.S. Food and Drug Administration sets the standards for the accuracy of the blood glucose meters that those of us who have diabetes rely on to keep our level in the right range. If our blood glucose gets too low we can fall into a coma, and if it goes to high we are more likely to get one or more of the awful complications of uncontrolled diabetes.

But few of us know what the standards are, judging from the messages that people with diabetes send me and what I read on the Internet. For years I have been writing about the need for our meters to be more accurate, but as I explored this key topic in depth I got more and more confused and told my friend Bennet Dunlap that.

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“The more confused you are the more you understand status quo,” he replied. Bennet is perhaps our leading diabetes advocate and has addressed the FDA directly on this issue. Bennet created Strip Safely and together with another diabetes patient advocate, Christel Marchand Aprigliano, co-founded the Diabetes Patient Advocacy Coalition.

The Current Accuracy Standard

The FDA regulates the medical devices that American use. Its accuracy standard for blood glucose meters is simple to state:

  • 95 percent of the blood glucose test results have to fall within ±15 mg/dl of the results of the reference measurement when the blood glucose level is less than 75 mg/dl
  • and
  • 95 percent of the results have to fall within ±20 percent when the blood  glucose level is more than 75 mg/dl

My sources for these statements include, in somewhat more technical terms, FDA Evaluation of Point of Care Blood Glucose Meters and FDA Evaluation of Glucose Meters: Considerations for Use in the Home. The term “reference value” means its known and correct measurement.

The standard itself is clear. But the issues surrounding it can provide some confusion.

But the Standard Isn't All

The FDA standard is the same as those set the International Organization for Standardization (known as ISO) set in 2003. But the FDA makes a point to say that the United States isn’t required to follow ISO, and in fact ISO set tighter standards in 2013. While the FDA proposed tighter standards last year, they haven’t been implemented.

“The regulatory standard in the United States did not advance with the world standard in 2013,” Bennet told me. “In fairness, there are many meters on the market here that meet the ISO 2013 standards. But we are still under the 2003 rules, behind just about everyone else. The US is at ±20 percent, and everyone else is at the tighter standard of ±15 percent.”

But there are two huge loopholes:

1. Before 1976 when Congress passed the Medical Device Amendments to the Food and Drug Act authorizing the FDA to regulate medical devices, we had no accuracy standards that home blood glucose meters had to meet. The law authorized the FDA to impose accuracy standards, but exempted the devices that were already on the market. At the same time section 510(k) of the legislation said that the FDA could approve a meter that was substantially equivalent -- just as good -- as one of the meters that were legally sold before the law went into effect.

Now, the FDA generally approves new blood glucose meters on the basis of section 510(k). Consequently, it's likely that some of the blood glucose meters on the market today aren’t required to meet them even now. When Bennet on my behalf contacted Stayce Beck, the chief of the FDA’s Diabetes Diagnostic Devices branch, she confirmed that “is the way the law is written.”

2. Bennet also emphasized another problem with the accuracy of our meters. After the FDA approves a meter and it comes to market, we don’t have a process to make sure that it meets the standards.

The Diabetes Technology Society estimates that one-fourth of the meters sold here fail to perform up to the standards that led to their approval. This is according to the society’s president, David Klonoff, who is also a clinical professor of medicine at the University of California, San Francisco.

Quality Costs Money

Wouldn’t it be great if the FDA had a higher accuracy standard. But quality costs money, and perhaps the accuracy that many of us would like our meters to have it isn’t yet available at any price.

For the home meters we use, “the technology isn't currently sufficient for manufacturers to meet +/-10% accuracy,” says Courtney Lias, Ph.D. She is the director of the FDA’s Division of Chemistry and Toxicology Devices. “In an ideal world, everyone would have a meter that's within 5-10% of the accuracy reference, but as it stands right now, if we called for that, manufacturers wouldn't be able to provide meters at all."

See more of my articles about how to manage diabetes:

Why Diabetes Advocacy Has a Problem

Comparing Diabetes Blood Glucose Meter Accuracy

Comparing Diabetes Blood Glucose Meters for Accuracy and Precision