Diabetes and cardiovascular disease

The International Diabetes Federation has estimated that approximately 1 in 11 adults (415 million adults) has diabetes mellitus globally. The global prevalence is expected to rise to 642 million adults by 2040. Over 90% of these cases of diabetes mellitus are due to type 2 diabetes. The main drivers of the global epidemic of type 2 diabetes include overweight and obesity, sedentary lifestyle, unhealthy dietary patterns, population aging, and changes in environment such as rapid urbanization. In the United States, more than 34 million people have diabetes, of which approximately 7 million remain undiagnosed.

Diabetes is a leading cause of increased mortality, reduced life expectancy, and has a major impact on quality of life across the world. The relationship between type 1 and type 2 diabetes mellitus and cardiovascular (CV) disease is well established. Atherosclerotic CV disease, defined as coronary heart disease, cerebrovascular disease, or peripheral arterial disease (PAD), is the leading cause of morbidity and mortality for individuals with diabetes. It is estimated that diabetes mellitus confers a twofold excess risk of adverse vascular outcomes (coronary heart disease, ischemic stroke, and vascular deaths), independent of other risk factors. Those individuals with long-standing diabetes, multiple other cardiac risk factors, and microvascular complications, such as renal disease, appear at greater risk for adverse CV events. After steady reductions in acute myocardial infarction (MI) and stroke among individuals with type 2 diabetes mellitus over the last two decades, recent trends suggest that ischemic complications may be increasing among younger adults with type 2 diabetes.

Diabetes is commonly present in individuals with acute and chronic coronary syndromes, and the presence of diabetes is associated with a worse prognosis in these individuals. Patients with diabetes experience an increased rate of early and late complications, including increases in mortality, reinfarction, and heart failure following acute coronary syndrome compared to those without diabetes. Individuals with diabetes are often older and have comorbid conditions, but the increased risk persists after adjustment for these differences.

The risk of PAD is increased approximately twofold to fourfold in individuals with diabetes. It is more commonly associated with femoral bruits and absent pedal pulses and with a high rate of abnormal ankle-brachial indices. The duration and severity of diabetes correlate with incidence and extent of PAD. The pattern of PAD in diabetic patients is characterized by a preponderance of infrapopliteal occlusive disease and vascular calcification. Clinically, PAD in diabetic patients manifests more commonly with claudication and also a higher rate of amputation—the most common cause of nontraumatic amputations. Approximately one-third of patients hospitalized with lower extremity arterial disease have diabetes.

Patients with diabetes also have a higher rate of intracranial and extracranial cerebrovascular atherosclerosis and calcifications. Diabetes is an independent risk factor for stroke, and individuals with diabetes have approximately a two- to fourfold increased risk of stroke compared to those without diabetes. Compared to individuals without diabetes, the risk of subsequent stroke, disability, stroke-related dementia, and mortality are increased.

CV complications in patients with diabetes can be the result of macrovascular disease, including CAD, PAD, and cerebrovascular disease, or can be due to microvascular disease that can result in nephropathy, retinopathy, and neuropathy. Patients with type 2 diabetes have greater atherosclerotic plaque burden, increased atheroma volume, and smaller coronary artery lumen than those without diabetes.