Prognostic value of admission blood glucose concentration and diabetes diagnosis on survival after acute myocardial infarction: results from 4702 index cases in routine practice

Abstract

The diagnosis of diabetes and admission blood glucose concentration are associated with adverse outcome after acute coronary syndromes. We compared the relative association with survival after ST elevation AMI (acute myocardial infarction) of admission blood glucose concentration and of diabetes diagnosis. We carried out a retrospective cohort study in 4702 consecutive patients with STEMI (ST elevation AMI) occurring from 1 April 1993 to 31 December 2005, assessed for mortality at 30 days and 1 year. Patients were classified according to antecedent diabetes and by blood glucose concentration at admission (quartile 1, <7mmol/l; quartile 2, 7–8.2 mmol/l; quartile 3, 8.3–10.9 mmol/l; quartile 4, ≥11 mmol/l). Multivariable models were constructed for determinants of mortality, including year of STEMI and demographic variables, entering blood glucose concentration and antecedent diabetes individually and together. All-cause 30-day and 1-year mortality were 22.8% and 31.3% for patients with antecedent diabetes, compared with 16.3% and 23.0% respectively for those without. For glucose quartiles 1, 2, 3 and 4, crude 30-day mortality was 9.0%, 10.6%, 17.9% and 31.0%. Adjusted 30-day mortality risk was similar in quartile 2, higher by >80% in quartile 3 and by >150% in quartile 4, compared with glucose quartile 1. Antecedent diabetes was associated with an increase in mortality [unadjusted odds ratio (OR) 1.52 (95% CI 1.24, 1.86)]. On multivariable analysis (excluding glucose quartile), this reduced to 1.24 (0.98, 1.58) and changed to a small, statistically non-significant reduction in risk when glucose quartile was added to the analysis [adjusted OR 0.87 (0.67, 1.13)]. Inclusion of antecedent diabetes in multivariable models did not add to the predictive value for mortality of glucose quartile (P=0.368). Similar relationships were observed for 1 year mortality. In patients with STEMI, blood glucose concentration shows graded association with risk of 30-day and 1-year mortality and is of greater prognostic relevance than antecedent diabetes diagnosis. Moderate elevation of blood glucose, below levels previously considered to be clinically relevant, is associated with adverse impact on survival.