Changes over Time in Hemoglobin A1C (HbA) Levels Predict Long-Term Survival Following Acute Myocardial Infarction among Patients with Diabetes Mellitus.

Frequent fluctuations of hemoglobin A1c (HbA) values predict patient outcomes. However, data regarding prognoses depending on the long-term changes in HbA among patients after acute myocardial infarction (AMI) are scarce. We evaluated the prognostic significance of HbA levels and changes among diabetic patients ( = 4066) after non-fatal AMI. All the results of HbA tests up to the 10-year follow-up were obtained. The changes (∆) of HbA were calculated in each patient. The time intervals of ∆HbA values were classified as rapid (<one year) and slow (≥one year) changes. The outcome was all-cause mortality. The highest mortality rates of 53.8% and 35.5% were found in the HbA < 5.5-7% and ∆HbA = -2.5-(-2%) categories. A U-shaped association was observed between HbA and mortality: adjOR = 1.887 and adjOR = 1.302 for HbA < 5.5% and ≥8.0%, respectively, as compared with 5.5-6.5% ( < 0.001). Additionally, ∆HbA was associated with the outcome (U-shaped): adjOR = 2.376 and adjOR = 1.340 for the groups of <-2.5% and ≥2.5% ∆HbA, respectively, as compared to minimal ∆HbA (±0.5%) ( < 0.001). A rapid increase in HbA (but not decrease) was associated with a greater risk of mortality. HbA values and their changes are significant prognostic markers for long-term mortality among AMI-DM patients. ∆HbA and its timing, in addition to absolute HbA values, should be monitored.