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Meters are Too Variable

By David Mendosa

Last Update: December 28, 2005

Researchers at the U.S. Centers for Disease Control and Prevention in Atlanta just finished their first study of blood glucose meters. They found that meters can vary significantly.

Strips are a big source of variability

They picked the five biggest selling meters in 2001, when they started this research. But the study didn’t rate those meters — the MediSense Precision, Ascencia Dex, Prestige Smart System, OneTouch Ultra, and Accu-Chek Advantage, says research chemist Dr. Mary Kimberly. She is the primary author of the article that the journal Clinica Chimica Acta will publish later in 2006. Their report is currently in press.

“The study was designed to see if there was a need for standardization,” Dr. Kimberly told me. Consequently, the study didn’t rate the meters, and she said she couldn’t tell me.

The researchers found a lot of variability — differences in repeated tests — among blood glucose meters and concluded that we do need standardization to reduce it. They primarily evaluated precision, the ability to give similar readings on successive tests of the same blood sample.

They didn’t study just meters. They also studied test strips that the meters use and found that the strips were a big source of variability.

“In our analysis the age of the strip lot had a lot to do with meter variability,” Dr. Kimberly says. “It is very important not to use expired strips,” she told me.

“But the variability among monitors can come from sources as well,” Dr. Kimberly says. “Use of different accuracy points is a source of variation among meters.”

Accuracy is simply the closeness of agreement with the true value. The problem with accuracy is that different lab standards or reference methods can provide different accuracy points.

“Just because a meter agrees with a specific reference method doesn’t mean that it’s accurate, unless that reference method is traceable to an appropriate higher order standard,” she says. That’s precisely what’s missing in any attempt to determine meter accuracy.

We lack standardization because we don’t have agreement yet on what our blood glucose numbers are based on. The article says that we don’t have that standardization yet for capillary whole blood, which meters use. Dr. Kimberly told me that the study didn’t look at accuracy, because the reference system isn’t completely developed.

Who’s going to do that? CDC has developed a whole blood reference method, but a whole blood reference material is still lacking. She says that the U.S. National Institute of Standards and Technology usually develops reference materials for blood and is likely to develop the capillary whole blood standard. It looks like I will be reporting on their work in a future column.

The HemoCue Standard
This CDC study of meter variability screened participants with a HemoCue 201 meter. It’s the gold standard meter, but only health care professionals can buy it. Still, about three years ago I got one from HemoCue, a Swedish company, and wrote about it then.

The company told me at that time that they would eventually have a meter for the U.S. home market. The CDC study reminded me to contact HemoCue again.

I learned that the company has just introduced its home meter in Sweden and that they and their meter are coming here soon. When I meet with them, I will report on it here. 

This article originally appeared in Diabetes Health, January 2006.

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