Researchers at the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta have just finished their first study of blood glucose meters. They found that meters could vary significantly.
When the CDC started their research, they picked the five top-selling meters for 2001—the MediSense Precision, Ascencia Dex, Prestige Smart System, OneTouch Ultra and Accu-Chek Advantage. But the study didn’t rate those meters, says Mary Kimberly, a research chemist. She is the primary author of an article that will be published later in 2006 in the journal Clinica Chimica Acta.
The researchers found a lot of variability— differences in repeated tests—among blood glucose meters and concluded that we need standardization to reduce it. They primarily evaluated precision, the ability to give similar readings on successive tests of the same blood sample.
The CDC didn’t study just meters. They also studied the test strips used by the meters and found that the strips were a source of much of the variability.
“In our analysis the age of the strip lot had a lot to do with meter variability,” Kimberly says. “It is very important not to use expired strips.” She adds, “But the variability among monitors can come from sources as well. 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,” Kimberly 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. Kimberly told me that the study didn’t look at accuracy, because the reference system isn’t completely developed.
Who’s going to develop it? Kimberly says that the U.S. National Institute of Standards and Technology is likely to develop the standard. It looks like I will be reporting on their work in a future column.
The HemoCue Standard
The CDC study of meter variability screened participants with a HemoCue 201 meter. It’s the gold standard meter, but only healthcare 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 prompted 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. I will report on my meeting with them in a future column.