Heart conditions are the most lethal complications of diabetes, but often their risk can be reduced. Diabetes is one of the four major risk factors – along with high blood pressure, smoking and abnormal cholesterol levels – for heart attack.
A heart attack can occur when the coronary arteries become blocked because of the buildup of plaque (atherosclerosis), restricting blood to the heart. This condition is called coronary artery disease (CAD). When blood flow to the heart stops, heart tissue begins to die. This event is called a heart attack.
Diabetes increases the risk of developing CAD in part because high levels of glucose (blood sugar) cause blood vessels to thicken and to lose their elasticity. People with diabetes tend to have CAD that occurs earlier in life and is more likely to be fatal.
People with diabetes are also at increased risk of many other cardiovascular diseases. These include peripheral arterial disease, cerebrovascular disease, stroke and heart failure. Although the majority of people with diabetes die of cardiovascular causes, many are unaware of the risks.
Diabetic patients can reduce their risk of heart conditions by controlling cholesterol, blood pressure and glucose through methods including exercise, quitting smoking, diet and medications prescribed by their doctor.
About diabetes and the heart
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.
Types and differences of heart conditions
Diabetes increases the risk of developing blood vessel disease throughout the body. Typically, blood vessel (vascular) disease involves damage or weakening of the blood vessel walls, which can make them vulnerable to a buildup of plaque. This process is called atherosclerosis. When this buildup occurs within the coronary arteries, which feed the heart muscle, the condition is called coronary artery disease (CAD).
CAD, the most common type of heart condition, can impede blood flow to the heart muscle. Inadequate blood flow can cause a number of conditions, including:
- Angina. A type of temporary chest pain, pressure or discomfort that occurs when the heart is not getting enough oxygen.
- Heart attack. Occurs when vessel blockages reduce or stop blood flow to the heart. The affected area of the heart stops working, weakening the heart. People with diabetes tend to have heart attacks that are more severe and occur earlier in life than nondiabetics.
- Heart failure. Over time, the heart may begin to struggle to supply the body with the blood it requires. Heart failure is a term used when the heart cannot meet the body’s needs. It is a chronic disease that is the result of other cardiovascular conditions, such as high blood pressure and cardiomyopathy (weakened heart muscle). Among women with coronary heart disease, diabetes has been shown to be the strongest risk factor for heart failure, according to the American Heart Association. Studies have found an increased risk of heart failure in people with the eye disease diabetic retinopathy.
High blood pressure is a major factor in many diabetic complications, such as diabetic nephropathy, retinopathy and glaucoma. It occurs when the force of blood against artery walls becomes excessive, which can affect entire body. In the heart, it is a cause as well as a consequence of atherosclerosis. High blood pressure is commonly diagnosed in patients with diabetes.
Diabetic vascular disease (diabetic angiopathy) can occur in other areas of the body. When it occurs in the peripheral arteries, the condition is called peripheral arterial disease (PAD). Diabetes and cigarette smoking are particularly strong risk factors for PAD, according to the American Heart Association. Cerebrovascular disease affects the blood vessels serving the brain and can lead to a stroke.
Diabetes is also a risk factor for several other cardiovascular conditions, including:
- Atrial fibrillation. An abnormal heartbeat (arrhythmia) that affects the heart’s upper chambers (atria). Complications of atrial fibrillation, the most common type of arrhythmia, can include blood clots, stroke, pulmonary embolism and heart failure.
- Cardiac arrest. A sudden, profound disturbance in the heart’s rhythm that makes the heart stop beating or slow to the point where the life is unsustainable. The leading cause of cardiac arrest is ventricular fibrillation (condition in which the heart’s lower chambers quiver instead of pumping blood) accompanied by CAD or other heart diseases.
- Anemia. An insufficient number of red blood cells, which carry oxygen throughout the body. Severe anemia can contribute to cardiomyopathy and heart failure. Recent research indicates that anemia affects many elderly people with type 2 diabetes, especially those with kidney disease or macroangiopathy. Anemia is also common in dialysis patients.
In addition, diabetes complicates recovery from cardiac surgeries such as a coronary artery bypass or a heart transplant. Recent research indicates that hyperglycemia increases the risk of blood clots and embolisms after surgeries such as a joint replacement.
Signs and symptoms of heart conditions
Heart conditions can cause a number of symptoms. These include:
- Chest pain due to reduced blood flow (angina), which may radiate to the neck, jaw, shoulder, arm or testicles
- Pressure in the chest
- Dizziness or fainting
- Abnormal heartbeat
- Gray facial color
- Abnormal heartbeat
- Shortness of breath or fatigue
- Edema (swelling) in ankles
- Pain or cramping in buttocks, thighs or calves during exertion (claudication)
- Erectile dysfunction
People with diabetes should also be aware of the signs of a stroke. These can include numbness or weakness in arms or legs (especially on one side of the body), difficulty communicating and sudden loss of vision.
Diagnosis methods for heart conditions
A physician is likely to take a medical history and to perform a physical examination when diagnosing heart conditions. If a heart condition is suspected, one or more of the following tests may be performed:
- Blood tests. A sample of blood taken from an artery or a vein to detect and measure various factors in the blood. These tests can be used to diagnose heart disease, establish if a heart attack has occurred, evaluate the extent of damage to the heart and monitor the patient’s progress during treatment.
- Electrocardiogram (ECG or EKG). A recording of the heart’s electrical activity as a graph or series of wavy lines on a moving strip of paper or video monitor.
- Chest x-ray. A painless test in which an image is created of the chest by using low doses of electromagnetic radiation that are reflected on film or fluorescent screens.
- Echocardiogram. A painless test that uses high-frequency sound waves (ultrasound) to get a picture of the heart chambers and valves.
- Exercise stress test. Used to find heart problems that are evident only during exercise. Also known as the “treadmill test,” the test involves an electrocardiogram that measures how the heart performs during exertion.
- Holter monitor. A small, portable device worn by a patient that records the heart’s electrical activity over a period of time.
- Coronary angiogram. An x-ray of the coronary arteries to see if any of those arteries are blocked, usually by fatty plaque. A catheter is used to inject dye into blood vessels. X-rays are then taken to look for blockages highlighted by the dye.
- CAT scan (computed axial tomography). A noninvasive or minimally invasive test that uses multiple x-ray images, taken from different angles, to create three-dimensional images of body structures.
- MRI (magnetic resonance imaging). Uses a powerful magnetic field to create images of structures and organs within the body. This noninvasive or minimally invasive test can help physicians diagnose a wide range of diseases and conditions without subjecting the patient to radiation or radioactive isotopes and often without needles or dyes.
- MUGA scan (multi-gated acquisition). Also known as a nuclear ventriculogram, the MUGA scan is a form of radionuclide imaging that provides the physician with a comprehensive look at blood flow and the function of the lower chambers of the heart.
Treatment options for heart conditions
In some cases, the risk of diabetic heart ailments can be significantly reduced through lifestyle modifications, such as:
- Regular exercise
- Good diet
- Quitting smoking
- Loss of excess weight
- Limiting alcohol
For many people with diabetes, lifestyle modifications alone are not enough to reduce the risk of heart conditions. There are many medications used to treat heart conditions related to diabetes. These include:
- Aspirin. The American Diabetes Association (ADA) recommends low-dose aspirin therapy for patients with diabetes at high risk for cardiovascular disease. However, some patients, such as those with stomach problems or kidney diseases such as diabetic nephropathy, may not be able to take aspirin. Individuals are advised to consult their physician for details about the benefits and risks of aspirin therapy.
- Other anticoagulants or antiplatelets, or clot-busting drugs.
- Antihypertensives. Medications that lower blood pressure and in some cases have other health benefits. Antihypertensives include:
- ACE inhibitors
- Angiotensin II receptor blockers (ARBs)
- Calcium channel blockers
- Beta blockers
- Alpha blockers
- Central adrenergic inhibitors
- Renin inhibitors
- Cholesterol drugs. Medications that improve levels of fats (lipids) in the blood, which include cholesterol and triglycerides. Types of cholesterol drugs include statins, bile acid resins, nicotinic acid (niacin), fibrates and cholesterol reabsorption inhibitors.
- Oral antidiabetic agents. Medications prescribed for many people with type 2 diabetes. Some of these drugs have been found to have heart benefits, others to have cardiac risks. Patients who take antidiabetic agents are advised to ask their physician about the possible cardiovascular benefits and risks of these medications.
- Angioplasty. A small balloon is attached to a tube and inserted into the blocked vessel. The balloon is then inflated, which opens the vessel. In some cases, a wire tube called a stent is inserted to keep the artery open.
- Coronary artery bypass graft (CABG). A vessel is taken from the leg, wrist or chest and attached to points above and below a blocked coronary artery. This allows blood flow to bypass a blockage and continue on to the heart.
Patients with end-stage heart disease may become eligible for a heart transplant. Long-term survival rates of heart recipients with uncomplicated, well-controlled diabetes are similar to those of nondiabetic recipients, recent research shows.
Prevention methods for heart conditions
Patients with diabetes can take many steps to decrease the likelihood of developing heart conditions. The most important measures include controlling glucose (blood sugar), blood pressure and cholesterol.
Keeping these factors in healthy ranges can dramatically lower the risk of developing diabetic heart conditions. The National Diabetes Education Program (NDEP) recommends the following readings for individuals with diabetes:
- Hemoglobin A1C level (measure of glucose control): Less than 7 percent
- Blood pressure: Less than 130/80 millimeters of mercury (mm/Hg)
- LDL (“bad”) cholesterol: Less than 100 milligrams per deciliter (mg/dL)
Other steps that can be taken include:
- Scheduling regular checkups. Heart conditions can usually be treated far more effectively when they are caught early. Physicians can monitor blood pressure and use blood tests to measure fat and cholesterol levels.
- Losing excess weight. Those who are overweight should shed pounds to reduce stress on the heart, blood pressure and LDL cholesterol.
- Exercise. Regular physical activity can help people lose weight, improve glucose control, and improve cholesterol and triglyceride levels. Patients should consult their physician before beginning an exercise program.
- Diet. Eating nutritious meals is essential to preventing heart conditions. Fiber-rich, minimally processed plant foods and monounsaturated fats such as olive oil and salmon can benefit the heart. Saturated fats and artificial trans fats are harmful. A registered dietitian can help diabetic individuals develop a lifetime eating plan that will work for them.
- Not smoking. Smoking doubles the risk of cardiovascular disease for patients with diabetes.
- Having good dental care. Recent research adds evidence to the connection between periodontal disease and cardiovascular disease.
- Taking medications as prescribed by a physician.
- Asking a physician about use of alcohol. Research has found some cardiovascular benefits in moderate use of red wine or other alcohol. However, alcohol can interfere with control of glucose, and excessive drinking can cause many health problems. Diabetic patients are advised to ask their physician how much alcohol, if any, they may drink.
- Considering preventive medication. The U.S. Food and Drug Administration (FDA) has approved the use of the cholesterol-lowering drug atorvastatin to reduce the risk of heart attack and stroke in people with type 2 diabetes who have risk factors for, but no signs of, cardiovascular disease. Some physicians routinely recommend statin drugs for most diabetic patients. In addition, patients may wish to ask their physician about the benefits and risks of aspirin therapy to help prevent heart disease.
Questions for your doctor on heart conditions
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about diabetes and heart conditions:
- What condition are my heart and blood vessels in?
- Do I need any tests to determine my cardiovascular fitness? If so, what will these tests involve?
- Do I have any cardiovascular problems? If not, what is my risk of developing them?
- How can I reduce my risk?
- What types of exercise should I do?
- Where should my blood pressure, cholesterol levels and glucose levels be?
- What is the difference between the types of cholesterol?
- What are the good fats and oils to eat and the bad fats to avoid?
- Do I need any cardiovascular treatments in addition to improvements in diet and exercise?
- Can any diabetes drugs benefit my heart?
- How do I know if a chest pain is angina?
- When should I seek medical help if I feel chest pain, dizziness, slurred speech or other possible symptoms of a cardiovascular problem?