Hemoglobin glycation index and in-hospital mortality after acute myocardial infarction in patients with/without diabetes: a prospective, nationwide, and multicenter registry

Background The effect of hemoglobin glycation index (HGI) on clinical outcomes in patients with coronary artery disease remains unclear. Purpose This study assessed the prognostic value of HGI for in-hospital mortality in acute myocardial infarction (AMI) patients with varied glucose metabolism status. Methods A total of 5,308 AMI patients were evaluated from China Acute Myocardial Infarction (CAMI) registry. HGI was calculated as the measured glycated hemoglobin A1c (HbA1c) minus the predicted HbA1c. The relationship between HbA1c and fasting plasma glucose (FPG) was assessed using linear regression analysis, which is presented as: HbA1c=0.272×FPG[mmol/L]+4.302 (Figure 1). Predicted HbA1c for each participant was calculated by inserting corresponding FPG levels into this regression equation. In both diabetic and nondiabetic populations, participants were categorized into low, moderate and high HGI groups based on their HGI levels. The primary endpoint was in-hospital mortality. Results Overall, 94 diabetic patients (4.5%) and 131 nondiabetic patients (4.1%) died during hospitalization. A significant difference in HGI was observed between patients who died during hospitalization and survivors in both diabetic and nondiabetic populations, with lower HGI values found in those who died. Restricted cubic splines analysis revealed an inverse J-shaped association between HGI and in-hospital mortality in diabetic population (P < 0.001 for nonlinearity), whereas a strong trend toward a linear negative association of HGI with in-hospital mortality was observed in nondiabetic population (P = 0.189 for nonlinearity). In both diabetic and nondiabetic populations, patients with low HGI had a significantly higher risk of in-hospital mortality compared with those with moderate HGI, whereas no significantly difference was found between high HGI and moderate HGI groups (Figure 2). In multivariable logistic regression analysis, the risk of in-hospital mortality was 2.774 times and 2.816 times in low HGI group than in moderate HGI group in diabetic and nondiabetic populations, respectively. Conclusions This study revealed an inverse J-shaped association between HGI and in-hospital mortality in AMI patients with diabetes, with an inflection point of HGI at 0.69%. In contrast, a linear negative association was observed between HGI and in-hospital mortality in AMI patients without diabetes. Further large-scale studies are necessary to assess the relationship between HGI and long-term mortality.Figure 1 Regression of FPG on HbA1c. Association of HGI and mortality.