At the Children with Diabetes convention at DisneyWorld in July Dr. Irl Hirsch announced that a new Accu-Chek device is the first good way that we have to measure glycemic variability, because it incorporates new low and high blood glucose indices. It's a big step forward, but the product's developer tells me that what it offers is something else.
Going beyond the simply measurement of our A1C level, glycemic variability is a measure of its quality. When we have a higher quality A1C, our levels are more steady, minimizing or avoiding high and low blood glucose levels.
The Accu-Chek Smart Pix Device Reader incorporates the low blood glucose index and the high blood glucose index that Dr. Boris Kovatchev, associate director of the University of Virginia Center for Biomathematical Technology, developed. Dr. Hirsch told his audience at the Children with Diabetes convention that the Smart Pix incorporates these indices as a much better tool for calculating glycemic variability than the standard deviation, which has been, well, the standard.
Dr. Hirsch's enthusiasm for the Smart Pix prompted me to obtain one of these devices. John Odegard, the marketing manager for Disetronic Medical Systems Inc. in Fishers, Indiana, kindly sent me one.
Disetronic, which like Accu-Chek is a Roche subsidiary, makes the D-TRONplus insulin pump, one of the devices that work with the Smart Pix. Accu-Chek also offers the Spirit insulin pump and six blood glucose meters - the Active, Aviva, Compact, Compact Plus, Advantage, and Comfort - all of which also work with the Smart Pix.
It connects to your computer just like a USB memory stick and is optimized to work with PCs, on which I tested it. While reportedly it runs on a Mac, I couldn't figure out how to do it on mine.
The Smart Pix is a great way for people with diabetes and their health care team to view and analyze blood glucose or insulin pump data quickly and conveniently.You have several distinct views to track readings or insulin delivery over different time periods and can visualize trends, patterns, peaks, and deviations from your desired blood glucose targets.
So that I could understand this new device better, John in Indiana connected me via conference call with the man in Germany who came up with the idea and brought it to market. Peter Blasberg, marketing manager for Roche Diabetes Care in Mannheim, Germany, explained to me that the Smart Pix incorporates both Dr. Kovatchev's low and high blood glucose indices and the standard deviation as well.
"I like Dr. Kovatchev's indices a lot because for frequent testers they tell you more about control than the A1C, which is insensitive to low values," Peter told me. "But it does not reflect hypoglycemic episodes and is not a measure of glycemic variability."
But Dr. Hirsch said that these indices are the best thing we have now to measure it. "We talked only briefly," Peter replied.
"I consider Dr. Kovatchev's indices rather valuable, if you prefer a condensed indicator instead of a detailed analysis of blood glucose values and trends," Peter continued. "Those two indices are far better than similar, but older attempts like the Schlichtkrull M-values or the mean amplitude of glycemic excursion (MAGE)."
We now have a lot of discussion about glycemic variability, Peter says. "But sometimes things are mixed up, and the low and high blood glucose indices do not demonstrate variability. Instead, they reflect the risk an individual has in terms of hypoglycemia - the acute risk - and hypoglycemia - the long-term risk. The two indices reflect this in an excellent way, but they are more reflective of exposure to high blood glucose and low blood glucose values. What Dr. Kovatchev has done with the two indices is to make blood glucose linear. But in terms of associated risk, the scale is not linear."
To make good use of Dr. Kovatchev's indices you need a lot of blood glucose tests. "My gut feeling is that you need a minimum of three tests per day to have good representative values on these indices," Peter says.
How does this compare with the A1C? The problem with that standard test is that hypos can positively influence it, so it doesn't reflect hyperglycemia properly.
"Therefore, the two low and high blood glucose indices are very well suited for patients who are testing regularly," Peter added. "At least, they are much more meaningful than mean blood glucose values. But for patients who test only rarely or not regularly, the A1C is still the better choice."
John tells me that Roche launched the Smart Pix in Europe in 2006 and in North America this June. It has a list price of $125 and is available through Disetronic and the diabetes product mail order distributors that carry Accu-Chek insulin pump products, including Liberty Medical Supply, Edgepark Medical Supplies, CCS Medical, and Gemco Medical. "And any of the companies that distribute Accu-Chek pump supplies can easily order the Smart Pix from us on behalf of their customers," John adds.
My conclusion is that while the low and high blood glucose indices may or may not be the best way we currently have to measure glycemic variability, the Smart Pix - which incorporates both of these indices as well as the standard deviation - is the best way that frequent testers have to measure their levels. And only with such measures can we control our diabetes.