Glycosylated hemoglobin measurement has been shown to be a potentially useful tool for both a variety of research applications and for the management of patients with diabetes mellitus. None of the methods available to quantitate glycosylated hemoglobins is ideal. We have reviewed a number of critical methodologie considerations for Chromatographie procedures including the effects of sample storage under various conditions, and the importance of removing labile components prior to analyses. We have developed a method for the colorimetrie determination of glycosylated hemoglobins that is more rapid than methods reported previously, that correlates well with results using high-performance liquid chromatogra-phy, and that can he standardized between laboratories. We have reviewed our experience using glycosylated hemoglobin in a large population of diabetic youths. We have presented a method for developing realistic goals for glucose control using glycosylated hemoglobin and for using glycosylated hemoglobin as a patient education and care reinforcement tool.