HbA1C test may not be useful among dialysis patients with diabetes

WINSTON-SALEM, N.C. — The gold standard long-term glucose monitoring test for patients with diabetes proved to be of limited value in dialysis patients, according to a new study at Wake Forest Baptist Medical Center released Wednesday.

While the American Diabetes Association has deemed the hemoglobin A1C test an effective tool for diagnosing diabetes, kidney doctors recently determined that the HbA1C test is not as useful for managing patients with diabetes and advanced kidney failure. Another test, the glycated albumin, or GA, assay appears to be far more effective in this setting.

“Many organs don't function properly in severe kidney failure," said Barry Freedman, John H. Felts III professor of internal medicine and lead investigator of the study. “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.

“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.”

Nearly 500,000 people are on dialysis in the United States, and diabetes is the cause of kidney failure in nearly 50% of them. Diabetes is the most common cause of kidney failure worldwide and is associated with high mortality rates — more than 20% of dialysis patients die each year.

Patients and physicians rely on the HbA1C test to measure an individual's average blood sugar level over the prior three months. It is the most commonly used long-term blood sugar test, and is widely trusted in the medical community.

Freedman suggested physicians not rely on the HbA1C in dialysis patients, instead suggesting that blood-glucose levels be monitored directly with multiple daily readings until the GA test is available in the states.