Biological variability of glycated hemoglobin

Background: The measurement of glycated hemoglobin (HbA1c) has a pivotal role in monitoring glycemic state in diabetic patients. Furthermore, the American Diabetes Association has recently recommended the use of HbA1c for diabetes diagnosis, but a clear definition of the clinically allowable measurement error is still lacking. Information on biological variability of the analyte can be used to achieve this goal. Methods: We systematically reviewed the published studies on the biological variation of HbA1c to check consistency of available data in order to accurately define analytical goals. Results: The nine recruited studies were limited by choice of analytic methodology, population selection,protocol application and statistical analyses. Conclusions: There is an urgent need to determine biological variability of HbA1c using a specific and traceable assay, appropriate protocol and appropriate statistical evaluation of data.