The article reports on the status of hemoglobin A1c (HbA1c) testing in end-stage renal disease (ESRD) patients. A brief historical overview of the use of hemoglobin A1c assay as a marker of glycemic control is given. Topics discussed include concordance of HbA1c with other tests of glycemia, limitations in chronic kidney disease and ESRD, and erythrocyte stimulation agents for patients with ESRD.