The heart is a muscular pump that transports blood throughout the body. Together, the heart and blood vessels compose the cardiovascular system. In the general population, the risk of disorders affecting the heart and cardiovascular system increases with age.

This process, which involves the buildup of plaque (atherosclerosis) within artery walls, occurs at a faster rate in patients with diabetes. High levels of glucose (blood sugar) damage the arteries, making them lose elasticity and causing them to narrow. As a result, blood pressure increases, placing further strain on blood vessels and organs throughout the body.

When this process occurs within the coronary arteries that serve the heart, the condition is called coronary artery disease (CAD). Patients with diabetes are two to four times more likely to develop CAD than nondiabetics, according to the U.S. Centers for Disease Control and Prevention (CDC). Furthermore, the type of plaque that develops in people with diabetes may be more dangerous.

Plaque is a mixture of fats (lipids) and other substances covered by a calcified cap. In patients with diabetes, this cap is thin and vulnerable to rupture by the rushing blood, particularly if the patient has high blood pressure. If this cap is shorn off, the fatty core within is exposed to the bloodstream, which can cause it to clot over again and further obstruct the blood vessel. In addition, pieces of plaque can travel to other vulnerable arteries, blocking them as well.

A heart attack (myocardial infarction) occurs when a coronary artery becomes blocked and heart tissue dies from lack of blood. Depending on the severity of the attack, the heart muscle may become seriously weakened (a condition called cardiomyopathy) and may eventually begin to fail, a condition called heart failure.

Cardiovascular diseases are the primary cause of premature death in patients with diabetes. At least 65 percent of people with diabetes die from heart disease or stroke, according to the CDC. The impact of diabetes on the heart has been compared to surviving a first heart attack among nondiabetics, because the risk of a second, possibly fatal, heart attack is that much greater.

These risks exist for people with either type 1 or type 2 diabetes. However, many of the risk factors for developing type 2 diabetes and related complications (e.g., obesity, high blood pressure and high cholesterol) are also the same for heart disease.

The CDC in 2006 reported that three of the four primary risk factors for cardiovascular disease - high blood pressure, dyslipidemia (unhealthy levels of blood fats) and smoking - declined dramatically in prevalence over the past three decades. However, the other one – diabetes – became more common.

Although type 1 diabetes cannot be prevented, patients who have elevated glucose levels but not yet type 2 diabetes (a condition called prediabetes) may be able to prevent or delay diabetes as well as heart disease.

People with lesser-known forms of diabetes, such as maturity-onset diabetes of the young (MODY) and latent autoimmune diabetes of adulthood (LADA), also face increased cardiovascular risks. Prediabetes has also been found to contribute to heart problems. Recent research indicates that prediabetic levels of hyperglycemia contribute to millions of deaths annually from cardiovascular disease. In addition, metabolic syndrome, a cluster of conditions that often include prediabetes, predisposes individuals to heart conditions.