Trusted Standard Glucose Test Not Best for Dialysis Patients
June 1, 2011. The most commonly used and trusted glucose monitoring test for diabetics – the hemoglobin HbA1c test — has been shown to be of limited value for dialysis patients, says a new study conducted at Wake Forest Baptist Medical Center. This study is scheduled for publication in the July issue of the Clinical Journal of the American Society of Nephrology.
Accurate blood sugar monitoring is essential for proper management of diabetes. The HbA1c test measures average blood suger levels over the 3 months prior to the test. It has long been considered reliable by patients and the medical community.
Although the HbA1c test is approved as an accurate tool for diabetes diagnosis by the American Diabetes Association, the discovery of its shortcomings for diabetic patients with advanced kidney disease is a recent finding by kidney specialists. A different test, called the glycated albumin or GA assay, is preferable in such patients.
Barry I. Freedman, M.D., John H. Felts III Professor and lead investigator in the new study said, “Many organs don’t function properly in severe kidney failure. For example, most dialysis patients have anemia, with fewer red blood cells than they should, which has a dramatic impact on the accuracy of the HbA1c reading.”
The HbA1c test works by reading the amount of blood sugar that interacts with the red blood cell hemoglobin in the bloodstream. This can only be accurate if the cells have normal lifespans, which is not the case for dialysis patients. Their red cells are short-lived, and this leads to lower HbA1c values.
Freedman explained, “Doctors long thought the HbA1c predicted outcomes in . This test is not predictive of outcomes in diabetes patients with kidney disease on dialysis. Dialysis patients and physicians get a false sense of security because their lower HbA1c actually relates to shorter red cell survival, yet suggests diabetes control is better than it really is.”
There are almost 500,000 persons on dialysis in the U.S., almost half of whom because of diabetes-caused kidney failure. Globally, diabetes accounts for the majority of kidney failure, and the death rates are high. Over 20% of those on dialysis die annually. Obviously, accurate blood sugar monitoring is needed for these patients.
In the Wake Forest study, Freedman and associates looked at over 400 diabetic dialysis patients. Normal treatment and HbA1c testing was uninterrupted, but the patients agreed to GA testing at 3 month intervals for an average period of 2.3 years-plus. The GA test, which was developed by Tokyo-based Asahi Kasei Pharma Corporation, tests blood sugar levels over the 17 day period before the test in contrast to the HbA1c test’s 3-month average. The GA, therefore is more accurate where rapid changes are occurring. It is currently used in Japan, South Korea, and China, but does not have FDA approval in the US.
The research compared the GA and the HbA1c test findings to discover their comparative value in predicting hospitalizations and survival. The HbA1c test was not a good predictor of these outcomes, while the GA produced good predictions for hospitalizations and patient survival. “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.”
Freedman’s advice to physicians is to place little reliance on the HbA1c test for their dialysis patients, but to directly monitor glucose with multiply daily readings until the GA test becomes available in the US.
If you have diabetes or kidney disease there are many things that can be done to help your situation. Contact Dr. Robert to learn more…
Dr. Robert Galarowicz
AIM Center
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Paramus, NJ 07652
201.618.3534
Rob@drrobertg.com