HbA1c is a predictive factor of severe coronary stenosis and major adverse cardiovascular events in patients with both type 2 diabetes and coronary heart disease

BACKGROUND: Coronary heart disease (CHD) is not only a macrovascular complication of type 2 diabetes mellitus (T2DM). Cardiovascular disease (CVD) is one of the leading causes of mortality among individuals with T2DM. Reducing the risk of adverse cardiovascular events (MACE) is crucial for the management of patients with CHD. This study aimed to investigate the effect of glycemic control on CHD severity and 3-point MACE (3p-MACE) risk in patients with T2DM and CHD. METHODS: 681 patients with both T2DM and CHD throughout October 2017 and October 2021 who were hospitalized in the second affiliated hospital of Nanchang university were included. A total of 300 patients were eventually enrolled in this retrospective cohort research. The severity of CHD in these patients was assessed, and the primary outcome during follow-up was recorded, with the primary result being the 3-point major adverse cardiovascular event (3p-MACE). The correlation between baseline glycated hemoglobin A1c (b-HbA1c) and the severity of CHD was evaluated by logistic regression analysis. The effect of b-HbA1c and follow-up HbA1c (f-HbA1c) levels on the risk of 3p-MACE were investigated by cox regression analysis. RESULTS: b-HbA1c was positively correlated with the severity of CHD (r = 0.207, p = 0.001), and patients with b-HbA1c > 9% were more likely to have severe CHD. The HRs for b-HbA1c and f-HbA1c on the risk of 3p-MACE were 1.24 (95% CI 0.94–1.64, p = 0.123) and 1.32 (95% CI 1.02–1.72, p = 0.036), respectively. Patients with f-HbA1c ≥8.6% had a higher risk of 3p-MACE than f-HbA1c < 8.6% (HR = 1.79, 95% CI 1.16–2.79, p = 0.009). CONCLUSION: In patients with both T2DM and CHD, b-HbA1c was an independent predictive factor of severe CHD. f-HbA1c was an independent predictive factor of 3p-MACE. Having the f-HbA1c below 8.6% significantly reduced the risk of 3p-MACE. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13098-023-01015-y.