Glycosylated Hemoglobin and Cardiovascular Risk in Nondiabetic Adults

Glycosylated hemoglobin (HbA_1c) is used most commonly as an indicator of glycemic control in patients with known diabetes. But do variations of HbA_1c level within the “normal” range predict diabetes and other clinical outcomes? To answer this question, researchers measured HbA_1c in 11,000 adults (mean age, 57) who had no histories of diabetes or cardiovascular disease and correlated HbA_1c levels with long-term outcomes.

When participants were grouped by baseline HbA_1c level, 15-year cumulative incidences of self-reported diabetes ranged from 6% for those with HbA_1c <5.0% to 44% for those with HbA_1c 6.0% to 6.5%. This association persisted after adjustment for baseline fasting glucose levels and other variables. Baseline HbA_1c also was associ…