Correlation between glycated hemoglobin and mean plasma glucose in hemodialysis patients

Since the half-life of red blood cells (RBCs) is shorter in hemodialysis patients, the value of glycated hemoglobin (HbA1c) as a marker of glycemic control in patients with diabetes on hemodialysis has recently been questioned. It is thought that it is not a good marker of mean plasma glucose (MPG) over a 3-month duration. In our current study, we evaluate whether monthly HbA1c values is a better marker of glycemic control than HbA1c every 3 months.

We performed a cross-sectional analysis of a retrospective cohort of 152 patients with diabetes who presented to two hemodialysis units in NYC. Patients had weekly predialysis glucose levels checked over the last 3 months, and HbA1c values were checked every 3 months. Data collection spanned a 6-month time frame from August 2008 to January 2009.

We found no difference in the correlation between HBA1c/mean plasma glucose (MPG) over the last month (MPG1m) and HbA1c/mean plasma glucose (MPG) over the last 3 months (MPG3m; r = 0.57 and r = 0.53, respectively; P = 0.212). Using multivariate analysis, reticulocyte count and weekly erythropoietin dose were found to independently and inversely effect the correlations HbA1c/MPG1m and HbA1c/MPG3m.

The value of HbA1c in hemodialysis for monitoring glycemic control is limited in the setting of a high reticulocyte count (>2%) and a high weekly erythropoietin dose. Checking HbA1c monthly versus every 3 months is not a better approximation of glycemic control in hemodialysis patients.