Q) Does anemia in CKD patients affect their A1C? Is A1C accurate in CKD patients?
Tight glycemic control is imperative for patients with chronic kidney disease (CKD), but the management of diabetes in CKD can be complex due to factors including anemia and changes in glucose and insulin homeostasis.
A1C is directly proportionate to the ambient blood glucose concentration and in the general diabetic population has proven to be a reliable marker.1 However, it may not be valid in patients with diabetes and CKD. Reduced red blood cell (RBC) lifespan, rapid hemolysis, and iron deficiency may lead to falsely decreased results.2 Decreased RBC survival results from an increase in hemoglobin turnover, which decreases glycemic exposure time.1 This process then lowers the amount of nonenzymatic glucose binding to hemoglobin.1 Folate deficiency caused by impaired intestinal absorption in CKD also affects RBC survival.3 Falsely increased results may be related to carbamylation of the hemoglobin and acidosis, both of which are influenced by uremia.2
Special considerations should be made for dialysis patients with diabetes. In hemodialysis patients, A1C may be falsely decreased due to blood loss, RBC transfusion, and erythropoietin therapy.3 Observational studies have shown that erythropoietin therapy is associated with lower A1C due to the increased number of immature RBCs that have a decreased glycemic exposure time.1 In peritoneal dialysis patients, A1C may increase after the start of therapy as a result of dialysate absorption.3
Research suggests that glycated albumin (GA) provides a short-term index of glycemic control (typically two to three weeks) and is not influenced by albumin concentration, RBC lifespan, or erythropoietin administration.1 A clear consensus on optimal levels of GA has not been established, but GA may be a more reliable marker of glycemic control in patients with diabetes and CKD. Further research is needed to establish a target GA level that predicts the best prognosis for patients with both conditions.1
A1C is the most reliable marker at this time, but special considerations should be made for the patient with CKD. Rather than focus on a single measurement, clinicians need to consider the patient’s symptoms and results from all labwork, along with A1C, to best evaluate glycemic control.4 Further research is needed in patients with diabetes and CKD to explore other reliable markers to help maintain tight glycemic control.
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