The concept of prediabetes (and similar concepts of impaired fasting glucose and impaired glucose tolerance) formally emerged in the 1990s to better characterize the incremental pathophysiology leading to the eventual development of diabetes.1 It is defined by ranges of disordered glucose values between normal and diabetes (eg, hemoglobin A1c levels, 5.7%-6.4% [to convert to the proportion of total hemoglobin, multiply by 0.01]). We treat it as a risk factor for diabetes; in midlife, those with a hemoglobin A1c level of 6.0% to 6.5% have 20 times the risk of developing diabetes compared with those with a hemoglobin A1c level of 5.0%.2