Age-related difference in the impact of diabetes mellitus on all-cause mortality after acute myocardial infarction

Aim: To test the hypothesis that the impact of diabetes mellitus on clinical outcomes after acute myocardial infarction (AMI) can vary by age. Methods: A total of 12,600 AMI patients from the Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH) between November 2011 and December 2015 was classified into young (n = 3,590 [29%]) and old (n = 9,010 [72%]). Those less than 55 years of age were considered young. We performed comparisons of baseline characteristics, in-hospital treatments, and 3-year clinical outcomes between patients with and without diabetes after stratification according to age group. Results: The prevalence of diabetes mellitus was 27% in the young AMI group. In the multivariable adjusted model of the entire cohort, diabetes mellitus was associated strongly with 3-year all-cause mortality (13% vs. 6.8%; adjusted hazard ratio [HR], 1.318; 95% confidence interval [CI], 1.138–1.526; P<0.001). When the entire cohort was subdivided into two age groups, young diabetic patients showed a 107% higher mortality rate than those without diabetes (adjusted HR, 2.07 [1.15–3.72]; P = 0.015). Meanwhile, old diabetic patients had a 25% higher risk of mortality than non-diabetic patients (adjusted HR, 1.25 [1.08–1.46]; P = 0.004). The interaction of diabetes with age was significant (adjusted P for interaction = 0.008). Conclusions: Diabetes mellitus is not uncommon in younger AMI patients, and the relative risk of 3-year mortality is significantly higher in young patients than in older counterparts. More aggressive treatments are needed to prevent future cardiovascular events in younger patients after AMI.