Relationship between fasting glucose levels and in-hospital mortality in Chinese patients with acute myocardial infarction and diabetes mellitus: a retrospective cohort study

Background: Previous studies have demonstrated that elevated admission and fasting glucose (FG) is associated with worse outcomes in patients with acute myocardial infarction (AMI). However, the quantitative relationship between FG levels and in-hospital mortality in patients with AMI remains unknown. The aim of the study is to assess the prevalence of elevated FG levels in hospitalized Chinese patients with AMI and diabetes mellitus and to determine the quantitative relationship between FG levels and the in-hospital mortality as well as the optimal level of FG in patients with AMI and diabetes mellitus. Methods: A retrospective study was carried out in 1856 consecutive patients admitted for AMI and diabetes mellitus from 2002 to 2013. Clinical variables of baseline characteristics, in-hospital management and in-hospital adverse outcomes were recorded and compared among patients with different FG levels. Results: Among all patients recruited, 993 patients (53.5 %) were found to have FG >= 100 mg/dL who exhibited a higher in-hospital mortality than those with FG < 100 mg/dL (P < 0.001). Although there was a high correlation between FG levels and in-hospital mortality in all patients (r = 0.830, P < 0.001), the relationship showed a J-curve configuration with an elevated mortality when FG was less than 80 mg/dL. Using multivariate logistic regression models, we identified that age, FG levels and Killip class of cardiac function were independent predictors of in-hospital mortality in AMI patients with diabetes mellitus. Conclusions: More than half of patients with AMI and diabetes mellitus have FG = 100 mg/dL and the relationship between in-hospital mortality and FG level was a J-curve configuration. Both FG = 100 mg/dL and FG < 80 mg/dL were identified to be independent predictors of in-hospital mortality and thus the optimal FG level in AMI patients with diabetes mellitus appears to be 80-100 mg/dL.