Effect of Hemoglobin A1c Change on 24-Month Clinical Outcomes in Patients with Diabetes after Acute Myocardial Infarction.

Background The average glycated hemoglobin (HbA1c) may not accurately reflect glycemic control status during the mid-term after acute myocardial infarction (AMI). We aimed to evaluate changes in HbA1c and their effect on mid-term clinical outcomes in patients with diabetes and AMI. Methods We enrolled patients with diabetes (n = 967) who underwent HbA1c measurement in the Korean nationwide registry. These patients were categorized into three groups based on changes in HbA1c from index admission to the 1-year follow-up visit: a decrease in HbA1c > 1%, changes in HbA1c within 1%, and an increase in HbA1c > 1%. Clinical outcomes at 24 months were examined. Results The baseline HbA1c levels were 8.55 ± 0.85, 7.00 ± 0.98 and 7.07 ± 1.05 (P = 0.001) and HbA1c levels after 1 year were 6.62 ± 0.73, 7.05 ± 0.98 and 9.26 ± 1.59 (P = 0.001) for patients with 3 groups, respectively. Patients with a 1% decrease in HbA1c had significantly lower incidence of major adverse cardiovascular events (MACE), cardiac death, and rehospitalization after 24 months than those with a 1% increase in HbA1c. However, in the Cox regression analysis, a >1% decrease in HbA1c change was not an independent factor for MACE, cardiac death, and rehospitalization. Conclusions Our analysis indicates that an HbA1c decrease of >1% within the first 12 months was not an independent prognostic factor until the 24-month mark. Therefore, standard diabetic control is recommended for patients with diabetes and AMI for up to 2 years.