The aim of this observational study was to assess long-term prognosis of a contemporary octogenarian population admitted to an Intensive Cardiac Care Unit with acute myocardial infarction (MI), and the prognostic value of two simple biomarkers obtained at admission: glucose blood level (ABG) and estimated glomerular filtration rate (eGFR). A total of 293 consecutive patients were included (202 with ST elevation MI and 91 with non-ST elevation MI) with median age 83.9 years, 172 (58.7%) male. The optimal cut-off points for all-cause death defined by ROC curves were ABG >186 mg/dL and eGFR 50 mL/min/1.73 m{}^2. The cohort was segregated into 3 groups according to these values: no biomarker present (group 1), either of the two biomarkers present (group 2) or both biomarkers present (group 3). Patients in group 3 were more frequently female, with worse Charlson index, Killip class and ventricular function, and higher GRACE scores. PCI was performed in 248 patients (84.6%). The highest in-hospital and long-term mortality, and composite MACE was observed in groups 2 and 3. All-cause mortality (median follow-up 2.2 years) was 44%. In multivariate analysis, ABG >186 mg/dL and eGFR 50 mL/min/1.73 m{}^2 were associated with a 4.2 odds ratio (OR) (Model 1: medical history variables) and 2.6 OR (Model 2: admission event variables) of mortality. The addition of these variables to ROC curves improved long-term risk prediction for Model 1 (C-statistics 0.718 versus 0.780, p = 0.006) and reclassification and discrimination in both models.