Biological variability of glycated hemoglobin

BackgroundThe 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.MethodsWe systematically reviewed the published studies on the biological variation of HbA1c to check consistency of available data in order to accurately define analytical goals.ResultsThe nine recruited studies were limited by choice of analytic methodology, population selection, protocol application and statistical analyses.ConclusionsThere is an urgent need to determine biological variability of HbA1c using a specific and traceable assay, appropriate protocol and appropriate statistical evaluation of data.