Type 2 diabetes mellitus is a chronic insidious process contributing to an overwhelming amount of morbidity and mortality, much of which is related to atherosclerosis, which often accompanies and complicates the natural history of diabetes. Although considerable attention has focused on new insights into diabetic mechanisms and emerging treatments, perhaps one of the greatest opportunities for decreasing the toll of diabetes and its late-stage complications may be intervening earlier in the disease process. Such notions redirect attention toward the concept of prediabetes mellitus as a potentially discrete syndrome, which may be identifiable in clinical practice. This article seeks to offer support for this hypothesis by considering the data surrounding prediabetes mellitus, with particular attention on the mechanistic and clinical links to atherosclerosis.