Changes over Time in Hemoglobin A1C (HbA1C) Levels Predict Long-Term Survival Following Acute Myocardial Infarction among Patients with Diabetes Mellitus

Frequent fluctuations of hemoglobin A1c (HbA(1C)) values predict patient outcomes. However, data regarding prognoses depending on the long-term changes in HbA(1C) among patients after acute myocardial infarction (AMI) are scarce. We evaluated the prognostic significance of HbA(1C) levels and changes among diabetic patients (n = 4066) after non-fatal AMI. All the results of HbA(1C) tests up to the 10-year follow-up were obtained. The changes ( increment ) of HbA(1C) were calculated in each patient. The time intervals of increment HbA(1C) values were classified as rapid (= one year) changes. The outcome was all-cause mortality. The highest mortality rates of 53.8% and 35.5% were found in the HbA(1C) < 5.5-7% and increment HbA(1C) = -2.5-(-2%) categories. A U-shaped association was observed between HbA(1C) and mortality: adjOR = 1.887 and adjOR = 1.302 for HbA(1C) < 5.5% and >= 8.0%, respectively, as compared with 5.5-6.5% (p < 0.001). Additionally, increment HbA(1C) was associated with the outcome (U-shaped): adjOR = 2.376 and adjOR = 1.340 for the groups of <-2.5% and >= 2.5% increment HbA(1C), respectively, as compared to minimal increment HbA(1C) (+/- 0.5%) (p < 0.001). A rapid increase in HbA(1C) (but not decrease) was associated with a greater risk of mortality. HbA(1C) values and their changes are significant prognostic markers for long-term mortality among AMI-DM patients. increment HbA(1C) and its timing, in addition to absolute HbA(1C) values, should be monitored.

Automated summary

This study evaluated the prognostic significance of HbA(1C) levels and changes among diabetic patients after non-fatal AMI. The results showed that fluctuations in HbA(1C) values, especially rapid increases, were associated with a higher risk of mortality. Monitoring both absolute HbA(1C) values and their changes could help predict long-term outcomes in AMI-DM patients.