Heart disease, particularly coronary heart disease (CHD) is a major cause of morbidity and mortality among patients with diabetes mellitus . The epidemiology of and risk factors for CHD and the frequency of silent myocardial ischemia in patients with diabetes will be reviewed here. Therapeutic issues are discussed separately. (See "Treatment of acute myocardial infarction in diabetes mellitus" and "Glycemic control for acute myocardial infarction in patients with and without diabetes mellitus" and "Coronary artery revascularization in patients with diabetes mellitus and multivessel coronary artery disease".)
Compared to individuals without diabetes, those with diabetes have a higher prevalence of coronary heart disease (CHD), a greater extent of coronary ischemia, and are more likely to have a myocardial infarction (MI) and silent myocardial ischemia.
Diabetes as a CHD equivalent — The National Cholesterol Education Program report from the United States and guidelines from Europe consider type 2 diabetes to be a CHD equivalent, thereby elevating it to the highest risk category [2,3]. This classification was based in part upon the observation that patients with type 2 diabetes without a prior MI (mean age 58) were at the same risk for MI (20 and 19 percent, respectively) and coronary mortality (15 versus 16 percent) as patients without diabetes who had a prior MI (mean age 56) (figure 1) . Similar findings have been noted in other studies. (See 'Myocardial infarction' below and "Treatment of lipids (including hypercholesterolemia) in secondary prevention", section on 'Identification of patients at risk'.)
The importance of the association between diabetes and CHD can be illustrated by findings from the Framingham Heart Study and the Multiple Risk Factor Intervention Trial (MRFIT). In the Framingham Heart Study, the presence of diabetes doubled the age-adjusted risk for cardiovascular disease in men and tripled it in women . Diabetes remained a major independent cardiovascular risk factor even when adjusting for advancing age, hypertension, smoking, hypercholesterolemia, and left ventricular hypertrophy.
Similar observations were noted in MRFIT . Among 5163 men who reported taking medications for diabetes (mostly type 2), 9.7 percent died from cardiovascular disease over a 12 year period; the comparable cardiovascular death rate in the 342,815 men not taking medications for diabetes was 2.6 percent. This difference was independent of age, ethnic group, cholesterol level, systolic blood pressure, and tobacco use. However, among diabetic men, the increase in cardiovascular risk rose more steeply than in nondiabetics with the addition of each of these risk factors.