Diabetes mellitus as a contributor to the risk of acute myocardial infarction

Abstract

The risk of nonfatal acute myocardial infarction (AMI) has been studied in relation to diabetes and other risk factors, combining data from three Italian case–control studies including 1,737 cases with nonfatal AMI and 2,317 controls in hospital for acute diseases unrelated to AMI risk factors. The multivariate odds ratio (OR) of AMI for diabetes was 2.3 (95% confidence interval, 1.8–2.9); the association with AMI risk was apparently stronger in patients diagnosed with diabetes when aged <40 years (OR 2.9), and in women (OR 4.4). When the combined effect of diabetes and other known risk factors on the risk of AMI was considered, compared to nondiabetic subjects with each factor at the lowest risk level, the OR for diabetic subjects was 4.7 in smokers, 2.8 in heavy coffee drinkers, 2.7 in those with higher body mass index, 3.4 in patients with high cholesterol levels, 3.3, 4.3, and 2.7 for diabetic subjects with history of hyperlipidemia, hypertension, and obesity, respectively, and 4.3 for those with a family history of AMI in first degree relatives. The association of each risk factor was much stronger in diabetic women. Preventive measures to reduce the prevalence of each additional risk factors in diabetic subjects could led to a substantial reduction of risk of AMI.

Introduction

Diabetes mellitus is a recognized risk factor for coronary heart disease 1, 2, 3, 4, 5, 6, 7, 8, the association being stronger in younger people 8, 9, 10, 11, 12 and in women 7, 8, 13.

Less information is available on the quantification of the risk of coronary heart disease in patients with diabetes simultaneously exposed to other risk factors, such as smoking, hypertension, hyperlipidemia, and obesity. A study, based on 582 cases of coronary heart diseases in diabetic subjects and 2,007 cases of coronary heart diseases in nondiabetic patients from the 1986 National Mortality Followback Survey, found that the relative risks of smoking and hypertension were similar in subjects with and without diabetes, while overweight showed a less strong association with coronary heart disease mortality in patients with diabetes than in those without diabetes [13]. A study conducted in Argentina on 1,060 patients with acute myocardial infarction (AMI) (164 of whom being also diabetic subjects), found an odds ratio (OR) of 2.0 for diabetes, and a multiplicative interaction of diabetes and smoking on the risk of AMI, leading to an OR of 9.3 [7]. Risk factors involved in the cardiometabolic syndrome in patients with diabetes include hypertension 14, 15, obesity (mainly central, i.e., high waist–hip ratio) 16, 17, atherosclerosis, dyslipidemia, hyperuricemia and endothelial dysfunction 14, 15. The Multiple Risk Factor Intervention Trial (MR-FIT), based on more than 5,000 patients with diabetes compared with 350,000 without diabetes followed for 12 years, found that systolic hypertension, elevated cholesterol levels, and cigarette smoking were independent predictors of cardiovascular mortality and that the presence of at least one of these risk factors had a greater absolute impact for increasing mortality in patients with diabetes than in those without diabetes [18].

To provide further quantitative information on the relation between diabetes and other recognized risk factors for coronary heart disease on the risk of AMI we have analyzed the results of a combined dataset from three case–control studies conducted in Italy.