A systematic review and meta-analysis of the effect of hyperglycemia on admission for acute myocardial infarction in diabetic and non-diabetic patients

INTRODUCTION: Regarding a potential relationship between diabetes and the prognostic significance of hyperglycemia in patients presenting with acute myocardial infarction (AMI), there is still debate. Therefore, we aimed in this study to demonstrate the effect of hyperglycemia on different outcomes in AMI patients, whether they are diabetic or not. METHODS: We searched PubMed, Web of Science, and Scopus using the following search strategy: "Diabetes" or "Diabetic" AND "Acute myocardial infarction" OR "AMI" AND "hyperglycemia" OR "glucose level" to find eligible articles that needed to go through the screening process for inclusion in our study. We conducted a meta-analysis of 19 included studies from Japan, Germany, China, the United Kingdom, and others using Review Manager version 5.4 software, pooling the mean difference in continuous variables, the number and total of dichotomous variables to measure the odds ratio (OR), and the generic inverse variance of OR or hazard ratio (HR) as reported in the included studies. RESULTS: The mean age of the participants ranged from 56.3 to 72.3 years old. The difference in blood glucose levels between diabetes and non-diabetes patients was found to be statistically significant, with an SMD of 1.39 (95%CI: 1.12, 1.66, p < 0.00001). In diabetic patients, hyperglycemia was statistically significantly associated with mortality, with a HR of 1.92 (95% CI: 1.45, 2.55, p < 0.00001) and an OR of 1.76 (95% CI: 1.15, 2.7, p = 0.01). In non-diabetic patients admitted with AMI, hyperglycemia was statistically significantly associated with mortality, with a HR of 1.56 (95% CI: 1.31, 1.86, p < 0.00001) and an OR of 2.89 (95% CI: 2.47, 3.39, p < 0.00001). AMI patients who were diabetic were statistically more likely to have a major adverse cardiovascular event (MACE) (HR = 1.9; 95% CI: 1.19-3.03; p = 0.007). AMI patients who were not diabetic were also statistically more likely to have a MACE (HR = 1.6; 95% CI: 1.15-2.23, p = 0.006). CONCLUSION: Hyperglycemia in AMI patients is a predictor of worse outcomes, including MACE and mortality, regardless of whether these patients are diabetic or not. In these patients, some factors act as predictors of mortality, including older age, higher glucose levels on admission, and a high Killip class.