Glycosylated hemoglobins result from post-translational changes in the hemoglobin molecule, and their levels correlate well with glycemic levels over the previous six to 10 weeks. Their use as an aid in monitoring diabetic control appears to be well established, but their value in predicting complications of diabetes and in diagnosing milder forms of diabetes is as yet unknown. Of the numerous methods available for the analysis of glycosylated hemoglobins, none has been evaluated extensively in a routine laboratory setting. However, liquid chromatography, isoelectric focusing, and radioimmunoassay techniques all give adequate results. For the purposes of monitoring long term diabetic control, assay of the fast hemoglobin fraction (AIa+b+c) appears adequate. However, for investigative purposes, when optimal sensitivity may be required, specific measurement of hemoglobin AIc is recommended.