In conclusion, the discovery of nonenzymatic glycosylation of proteins has opened new horizons in all aspects of diabetes management and research. The field is young. Advances in the understanding of the role of this phenomenon in the pathogenesis of diabetic complications and in the quantitating of its occurrence in various bodily proteins, come monthly. The nonenzymatically glycosylated protein markers, because they offer increased internal validity and precision, afford significant advantages over the classical measures of hyperglycemia. By providing improved means of assessing cumulative hyperglycemia, they will contribute to a better understanding of the relationship of diabetes to its chronic complications. They may also lead to an appreciation that mild hyperglycemia plays a substantial causal role in diseases, such as cardiovascular, with which diabetes has been traditionally associated. A variety of nonenzymatically glycosylated proteins exist, applicable to different purposes. Stored sera may well allow their retrospective determination in studies conceived of and/or executed without an appreciation of their potential. It behooves epidemiologists interested in any aspect of diabetes or in diseases for which diabetes is a relevant study factor, to become familiar with the process, measurement, and potential value of nonenzymatic glycosylation of proteins.