June 01--The standard test for measuring blood-sugar control in diabetes patients has limited value for those on dialysis, according to a study released Tuesday by Wake Forest Baptist Medical Center.
Dr. Barry Freedman, the lead researcher of the study, said that the findings could have far-reaching implications considering "dialysis patients and physicians get a false sense of security" about how the current test, HbA1c, rates diabetes control.
The Wake Forest researchers found that another option, glycated albumin or GA assay, appears to be a more effective test for dialysis patients.
Dr. Lynda Szczech, president of the National Kidney Foundation, said that the research could be pivotal because "we need measures to understand how good a job we are doing in controlling blood sugar in people with diabetes."
"If you can't measure what you are doing, you can't do it well."
Nearly 500,000 people are on dialysis in the Unites States, with diabetes the cause of kidney failure in nearly 50 percent of them.
The HbA1c test is the most commonly used for monitoring blood sugar over the long term and is considered as an effective tool for diagnosing diabetes.
Researchers assessed the two tests' ability to predict hospitalizations and survival. They found HbA1c failed to predict those outcomes, while the GA "was a strong predictor of patient survival and hospitalizations."
"This is the first study showing that a blood-sugar test predicts risk of death in diabetic dialysis patients, as well as risk of hospitalization," Freedman said.
"This test provides the missing link that will allow dialysis patients and physicians to accurately gauge risk. The association is clear: High GA readings predict higher risk."
The challenge with carrying out the recommendation is the GA test has not been approved by the Food and Drug Administration. It has been approved in China, Japan and South Korea.
Freedman suggests that physicians stop relying on the HbA1c test for dialysis patients, instead encouraging that blood-glucose levels be directly monitored with multiple daily readings until the GA test is available domestically.
The study is a follow-up to a report Wake Forest Baptist released in February 2008 that suggested the standard test for measuring blood-sugar control in diabetes patients, the hemoglobin A1c test, may not be accurate for those on the machine form of dialysis.
Although the manufacturer of the GA test, Asahi Kasei Pharma Corp. of Tokyo, helped sponsor both studies, Freedman said that the researchers wrote the entire protocol. Data collection and analyses were performed at the medical school.
"They had no influence on the findings and the study," Freedman said. "We determined through our research that we need to move to this test as the standard."
Controlling blood sugar is important because a high level is considered a risk factor for hardening of the arteries, which can lead to higher rates of kidney disease, heart attack, stroke, nerve damage and blindness, the researchers said.
Researchers evaluated 444 patients with diabetes undergoing dialysis at facilities in the Wake Forest Baptist system or affiliates. The patients continued their normal treatment and HbA1c monitoring, but also agreed to undergo a GA test every three months.
The evaluations took place over a 27-month period ranging from early 2007 through Sept. 15, 2009, with 156 patient deaths occurring during the study. Freedman said that the mortality toll was expected, considering that more than 20 percent of diabetes patients on dialysis die every year.
Blood sugar chemically interacts with the hemoglobin to identify a value for HbA1c.
However, HbA1c results are only accurate when red cells have a normal lifespan. Dialysis patients have shorter red-cell survival, reducing the time that sugar in the bloodstream has to interact with hemoglobin, thus causing lower HbA1c values.
The GA test measures blood sugars over the past 17 days, giving what Freeman calls a more accurate picture of diabetes control.
The study appears online in the Clinical Journal of the American Society of Nephrology -- http://cjasn.asnjournals.org/.
------ rcraver@wsjournal.com
(336) 727-7376
-----
To see more of the Winston-Salem Journal, or to subscribe to the newspaper, go to http://www2.journalnow.com/.
Copyright (c) 2011, Winston-Salem Journal, N.C.
Distributed by McClatchy-Tribune Information Services.
For more information about the content services offered by McClatchy-Tribune Information Services (MCT), visit www.mctinfoservices.com.