HbA1c Test Underestimates Glucose Control in Hemodialysis Patients

The standard hemoglobin A1c test (HbA1c) for estimating blood sugar control in people with diabetes is not accurate in those undergoing kidney hemodialysis.

HbA1c measures the percentage of hemoglobin (a protein in erythrocytes) that has reacted with glucose. This measure, also known as glycosylated hemoglobin, generally reflects blood sugar control over the previous 30-120 days.

A study, performed by researchers at Wake Forest University Baptist Medical Center (Winston-Salem, NC, USA), evaluated the HbA1c test 307 patients with diabetes, 258 with end-stage kidney disease on hemodialysis, and 49 who did not have kidney failure. The standard HbA1c test was compared with a newer test (glycated albumin [GA]), which measures the amount of blood sugar that has reacted with albumin, a protein in the plasma. The GA test reflects blood sugar control over the previous three to four weeks. Blood samples were also analyzed to determine recent blood sugar levels.

Compared to those without kidney failure, diabetic patients on hemodialysis had higher blood sugars and GA levels, despite lower HbA1c results. The relationship between GA and HbA1c differed between diabetic dialysis patients and those without kidney disease, indicating that the HbA1c did not accurately reflect blood sugar control in those on hemodialysis.

The major reason for the discrepancy appears to be that HbA1c depends on erythrocyte survival and these cells do not live as long in hemodialysis patients. Most dialysis patients have anemia requiring treatment with medications that stimulate erythrocyte production (erythropoietin).

Controlling blood sugar is important because high levels are risk factors for developing atherosclerosis and lead to higher rates of kidney disease, heart attack, stroke, nerve damage, and blindness. People with diabetes who undergo hemodialysis are especially at high risk. About one out of four diabetic dialysis patients (23%) in the United States will die from cardiovascular and infection complications during their first year on dialysis, and only 31% survive five years.


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Wake Forest University Baptist Medical Center