Type of discrepancy between glycosylated hemoglobin and fasting plasma glucose is associated with in-hospital outcomes in patients with acute coronary syndrome and diabetes: findings from the Improving Care for Cardiovascular Disease in China - Acute Coronary Syndrome (CCC-ACS) Project

Background The discrepancy between glycosylated hemoglobin (HbA1c) and fasting plasma glucose (FPG) in clinical practice may be related to factors such as acute stress, renal dysfunction, and anemia, and its relationship with in-hospital outcomes is uncertain. The aim of this study is to investigate the association between the type of discrepancy between HbA1c and FPG and in-hospital outcomes in patients with acute coronary syndrome (ACS) and diabetes. Methods The Improving Care for Cardiovascular Disease in China - Acute Coronary Syndrome (CCC-ACS) project is a national, hospital-based quality improvement project with an ongoing database. Patients with ACS, diabetes and complete HbA1c and FBG values at admission were included. The consistent group included patients with HbA1c < 6.5% and FBG < 7.0 mmol/L or HbA1c ≥ 6.5% and FBG ≥ 7.0 mmol/L. The discrepancy group included patients with HbA1c ≥ 6.5% and FBG < 7.0 mmol/L (increased HbA1c group) or HbA1c < 6.5% and FBG ≥ 7.0 mmol/L (increased FBG group). Results A total of 7,762 patients were included in this study. The numbers of patients in the consistent group and discrepancy group were 5,490 and 2,272 respectively. In the discrepancy group, increased HbA1c accounted for 77.5% of discrepancies, and increased FPG accounted for 22.5% of discrepancies. After adjusting for confounders, patients in the increased FPG group had a 1.6-fold increased risk of heart failure (OR, 1.62; 95% CI, 1.08–2.44), a 1.6-fold increased risk of composite cardiovascular death and heart failure (OR, 1.63; 95% CI, 1.09–2.43), and a 1.6-fold increased risk of composite major adverse cardiovascular and cerebrovascular events (MACCEs) and heart failure (OR, 1.56; 95% CI, 1.08–2.24). Conclusions Patients with an increased FPG but normal HbA1c had a higher risk of in-hospital adverse outcomes than those with increased HbA1c but normal FPG. This result may indicate that when HbA1c and FPG are inconsistent in patients with ACS and diabetes, the increased FPG that may be caused by stress hyperglycemia may have a more substantial adverse effect than increased HbA1c, which may be caused by chronic hyperglycemia. These high-risk patients should be given more attention and closer monitoring in clinical practice.