The Hemoglobin A1c has proven to be one of the most utilized and helpful tests in the management of diabetes. Instead of relying on random blood sugars to adjust a diabetic’s insulin regimen, the HgbA1c (which increases in the setting of poorly-controlled diabetes due to increased glycosylation of hemoglobin molecules in red blood cells, which have a half-life of 120 days) provides a more long-term and balanced view on glucose control.
However, there are some serious caveats to its use in dialysis patients. Because erythropoietin-stimulating agents will increase the proportion of young RBCs in the circulation, the HgbA1c significantly underestimates glucose levels in diabetic patients. This appears to be true across a wide range of glucose concentrations. It is probably more accurate to rely on serial serum glucose readings to help manage insulin regimens for ESRD diabetics, and there is also some data on the use of glycosylated albumin in the monitoring of this population. As diabetes is now the most common cause of ESRD in the U.S. and many patients rely on their nephrologist as their primary care doctor, this is an important finding.