Is HbA1c A Reliable Test In Patients With Diabetes And Renal Disease?

Melissa L. Adams, DPM

   A study by Inaba and co-workers reported a significantly lower value of HbA1c relative to plasma glucose and GA in hemodialysis patients with diabetes in comparison to patients with diabetes and without chronic renal failure (CRF).5 This study suggests that the measurement of HbA1c would result in underestimation of glycemic control in hemodialysis patients with diabetes.

   The authors further explained the mechanism for the significantly lower HbA1c value being due to anemia and/or erythropoietin injections in their patient population. An analysis validated that the erythropoietin use, rather than hemoglobin reduction, was an independent factor significantly associated with the HbA1c value. This study found significantly lower HbA1c values in hemodialysis patients who had diabetes and underwent treatment with erythropoietin in comparison to those on hemodialysis without diabetes. Furthermore, the plasma glucose and GA were not significantly different between the study groups.5

   Fukuoka and colleagues performed a prospective follow-up study, which showed a significant association between hyperglycemia and poor survival. This association was reflected by higher GA levels but not by HbA1c levels.8

   Glycated albumin is not only a significant indicator of hyperglycemia but also acquires biologic properties linked to the pathogenesis of diabetic vascular complications. This allows GA to aid in predicting the development of vascular complications in hemodialysis patients with diabetes.5

   Yamada and co-workers found a significant association with the presence of peripheral vascular calcification in hemodialysis duration and GA.11 When researchers replaced GA with HbA1c in the same model, the association was not significant. It is their work which suggests that glycated albumin might be a better indicator of glycemic control than HbA1c, and raises the possibility that improving glycemic control might aid in the prevention against the development of peripheral vascular calcification in patients with diabetes who are on hemodialysis.

   As with HbA1c, glycated albumin is not the best evaluation of glycemic control in all populations. One must take care in using the percentage of GA as the best prognostic indicator for glycemic control in special populations with abnormal turnover of serum albumin. These patients would include those with heavy proteinuria, liver cirrhosis, thyroid disease, inflammatory diseases or those on peritoneal dialysis.4,5

In Conclusion

   Although HbA1c holds the promise of more efficient patient care and improved management of diabetes, it is not a reliable form of assessing glycemic control in patients on hemodialysis.5,8,10 Furthermore, one should not use HbA1c as a diagnostic indicator of diabetic management in those on hemodialysis.

   Recent studies argue that GA is the way toward the future evaluation of glycemic control with its more reliable reflection of blood glucose control in patients with diabetes and end-stage renal disease in comparison to HbA1c.8,9 Future investigations are needed as the search continues for a reliable method of evaluating glycemic control in both patients with diabetes and diabetics requiring hemodialysis.

Dr. Adams is a third-year podiatry resident within the INOVA Fairfax Podiatric Residency Program in Falls Church, Va.

Dr. Steinberg is an Assistant Professor in the Department of Plastic Surgery at the Georgetown University School of Medicine in Washington, D.C. Dr. Steinberg is a Fellow of the American College of Foot and Ankle Surgeons.

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