The China Cardiovascular Disease Care Collaborative (CCC) project has shown that the prevalence of diabetes and prediabetes among patients with ACS is as high as 37.6%. Furthermore, ACS patients with comorbid diabetes or prediabetes have a 1.5-fold increased risk of MACE and a 2-fold increased risk of all-cause mortality [17]. The 2017 European Society of Cardiology (ESC) Guidelines for the management of ST-elevation myocardial infarction (STEMI) [18] and the 2020 ESC Guidelines for the management of non-ST-elevation acute coronary syndromes (NSTE-ACS) [19] both recommend risk stratification of patients with Acute Myocardial Infarction (AMI). Early risk stratification is of significant importance for selecting optimal secondary prevention medications. Currently, the primary risk model for predicting MACE in patients with ACS is the Global Registry of Acute Coronary Events (GRACE) score [20]. However, there is currently no risk assessment model designed explicitly for predicting MACE in ACS patients with comorbid diabetes. Additionally, when the GRACE score is used in the diabetic population, it lacks laboratory markers that reflect inflammation, oxidative stress, and other pathophysiological aspects related to metabolic diseases [20], and its predictive accuracy is insufficient to provide timely and accurate clinical evidence for drug intervention. Therefore, it is of great significance to identify objective indicators that reflect the prognosis of diabetic patients with concomitant ACS and utilize them to screen the risk of MACE occurrence, and this will provide meaningful guidance for clinical treatment and improve patient outcomes.
Research shows that in the diabetic population, high-frequency and high-amplitude glycemic variability enhance oxidative stress, triggering an intensified inflammatory response that exacerbates endothelial damage within blood vessels. This damage to the coronary endothelium may even be more severe than the damage caused by persistent hyperglycemia [5–8]. The results of the study conducted by Lim S [21] suggest that higher glycemic variability is a significant risk factor for MACE in diabetic patients. Sungha Park [22] found that higher glycemic variability during hospitalization was associated with all-cause mortality within one year in diabetic patients with comorbid cardiovascular disease.
Therefore, based on previous research findings, the GDI has an Area Under the Curve (AUC) of 0.901 (95% CI, 0.856–0.945) for screening abnormal glycemic variability, with a sensitivity of 0.781, specificity of 0.905, and a cut-off value of 4.21 [14], our research team believes that the GDI demonstrates good efficacy in screening abnormal glycemic variability and may serve as a predictive factor for the risk of MACE in diabetic patients with concomitant ACS.
In this study, the GDI values of patients in the MACE group were analyzed and compared to those in the non-MACE group. It was observed that the median, upper quartile and lower quartile of the GDI values in the MACE group were higher than those in the non-MACE group. Subsequently, the study population was divided into four groups based on the ascending order of their GDI values, ranging from low to high. The incidence of MACE gradually increased from the first group to the fourth group, indicating a progressive rise in MACE occurrence with increasing GDI values. Multivariable COX proportional hazards regression was used to investigate whether GDI is a risk factor for MACE in diabetic patients with concomitant ACS. Results revealed that GDI, STEMI, TC, TG, LDL, and Hs-CRP could independently predict the risk of MACE occurrence in diabetic patients with concomitant ACS.
Moreover, GDI, STEMI, and TC are identified as risk factors for the occurrence of MACE. However, the study results showed that TG, LDL, and Hs-CRP are protective factors, which is inconsistent with conventional beliefs. In the studies conducted by Subin Lim [21] and Marjo Okkonen [23], an inverse relationship between plasma lipids and the risk of MACE occurrence was also observed. Some scholars believe that this may be related to higher cardiovascular disease prevention and treatment awareness among patients with elevated plasma lipid levels. Our research group believes that although the lipid infiltration theory has been recognized as an essential mechanism in the development of coronary artery disease, the widespread use of lipid-lowering drugs has made plasma lipid levels no longer reflect the actual lipid metabolism status of patients. Therefore, coronary heart disease risk assessment models such as China-PAR Project [24] and UK QRISK [25] do not include any plasma lipid-related laboratory parameters but only consider "the use of lipid-lowering drugs" as an assessment factor. These phenomena may be influenced by lipid substances such as Small Dense LDL [26] and Remnant Lipoprotein Cholesterol [27] that have been proposed in recent years, the specific mechanisms behind these effects require further in-depth research in the future.
Regarding the analysis of Hs-CRP as a protective factor for MACE in this study, our research group believes that although Hs-CRP is a recognized cardiovascular disease biomarker. Many clinical studies consider it as an independent risk factor for cardiovascular disease. Previous studies have focused on healthy individuals or sub-healthy individuals who have previously experienced ACS but were asymptomatic at the time of inclusion in the study cohorts [28]. In contrast, the subjects of this study are diabetes patients admitted for ACS occurrence. Research reports have shown that Hs-CRP levels in ACS patients are significantly higher than those in stable angina patients and healthy individuals [29]. Hs-CRP peaks on the second day after the occurrence of ACS and is much higher than the reference value. Moreover, the relative variability of hs-CRP levels within one year after ACS occurrence can reach up to 206.1% [30]. Therefore, the Hs-CRP levels detected in this study may be considerably higher than those of patients in non-stressful states, resulting in a contradiction between the research findings of Hs-CRP in this study and traditional beliefs. It is worth noting that recent research has revealed the high variability of hs-CRP even in asymptomatic and clinically stable ACS patients [30], factors such as obesity, short-term temperature fluctuations, genetic polymorphism of the angiotensinogen gene, as well as the expression levels of miR−27a and miR−329 in peripheral blood monocytes, can all influence hs-CRP levels [31–34], therefore, taking individual differences into account, continuous periodic monitoring of hs-CRP values and evaluating them based on the mean level of hs-CRP may potentially yield more accurate assessment results in cardiovascular disease risk assessment.
In this study, GDI was identified as a simple screening index for abnormal glycemic variability. It was considered the leading risk factor for the occurrence of MACE in diabetic patients with concomitant ACS in multivariate COX proportional hazards regression. In Kaplan-Meier survival analysis, within the follow-up period, the cumulative risk of MACE occurring within 12 months in the high GDI group gradually exceeds that of the low GDI group. Furthermore, the abnormal GDI group demonstrates a significantly faster increase in the cumulative risk of MACE occurrence within 12 months than the normal GDI group, further confirming the close association between GDI and the risk of MACE occurrence in diabetes patients with concomitant ACS.
In summary, when the GRACE score, Hs-CRP, and traditional lipid parameters are not suitable for evaluating the risk of MACE occurrence in diabetes patients, the level of glycemic variability serves as an important indicator reflecting the pathological levels of oxidative stress, inflammation, and other factors within the bodies of diabetes patients, close monitoring of this level can help improve the prognosis of diabetes patients with concomitant ACS. In this study, the GDI has been confirmed as an independent predictor for the occurrence of MACE within 12 months in diabetes patients with concomitant ACS. Additionally, monitoring GDI values is simple, cost-effective, and demonstrates high clinical applicability. Therefore, in clinical practice, paying attention to the GDI value of patients, along with their clinical symptoms and physiological and biochemical indicators, and conducting a comprehensive assessment of the risk of MACE occurrence in diabetes patients with concomitant ACS is crucial, early implementation of primary and secondary preventive treatments holds significant importance in improving patient prognosis.
Limitations of this study include: (1) being a single-center observational study, which requires further expansion of the sample size and the conduct of multi-center studies to validate the reliability of the results and the predictive threshold; (2) solely recording the GDI indicators of patients upon admission, without conducting dynamic monitoring of GDI throughout the patient's treatment course.