Association of mean blood glucose, glycemic variability, and their combined effect with 28-day mortality in critically ill ICU patients with acute myocardial infarction: a MIMIC-IV retrospective cohort study.

Background: Dysglycemia is frequent in critically ill patients with acute myocardial infarction (AMI) and is linked to adverse outcomes. However, the relative contributions of sustained hyperglycemia and short-term glucose fluctuations, as well as their combined effects, remain incompletely defined in the intensive care unit (ICU). Therefore, this study aimed to investigate the independent and joint associations of mean blood glucose (MBG) and glycemic variability (GV) with 28-day mortality in critically ill ICU patients with AMI. Methods: We conducted a retrospective cohort study using the MIMIC-IV database, including adult ICU patients with AMI. MBG and GV, defined as the mean and standard deviation of all glucose measurements during ICU stay, were calculated prior to outcome occurrence. The primary outcome was 28-day all-cause mortality. Multivariable Cox models were used with adjustment for demographics, comorbidities, laboratory variables, illness severity, and ICU treatments. Results: Among 1,817 patients, 374 (20.6%) died within 28 days. The mean age was 70.4±12.8 years, and 66.2% were male. Higher MBG and GV were independently associated with mortality [adjusted hazard ratio (HR) per 10 mg/dL increase: 1.15 (95% CI: 1.12-1.18) and 1.03 (95% CI: 1.01-1.06), respectively]. In joint analyses, patients with high MBG and low GV had the greatest risk. Risk patterns differed according to diabetes status. Conclusions: In critically ill ICU patients with AMI, both MBG and GV are independently associated with short-term mortality, with a stronger association observed for MBG. Considering both metrics may improve risk stratification and support individualized glycemic management.