Diabetes and Coronary Artery Disease
Circulatory problems—heart disease, vascular disease, and stroke—affect more than 50 million people worldwide and accounts for more than 40% of all deaths. People with diabetes are three times more likely to die of cardiovascular disease than the general population. And problems with circulation lead to other problems with all parts of the body that depend on a healthy blood supply to function properly.
You are probably tired of hearing your doctor tell you that if you control your blood glucose you are more likely to avoid the complications of diabetes. But it’s true. That’s because the sugar in your blood makes your blood sticky. And when your blood is thick and sticky, it can’t flow well. That’s why chronically high levels of blood glucose can increase the risk of cardiovascular disease and other complications of diabetes.
Even if you have controlled your diabetes, you may at some point develop cardiovascular disease or other problems related to circulation. The good news is that new treatments and procedures are emerging all the time. Any time you have a problem related to poor circulation, it is important to seek treatment as soon as possible to keep the problem from getting worse and causing more problems.
DIABETES CORONARY ARTERY DISEASE
When you heart muscle doesn’t get the blood it needs, you can develop coronary artery disease. This usually happens because something is blocking the blood vessels to the heart. As a result, your heart is deprived of vital oxygen and nutrients carried by the blood. In its mildest form, this could result in angina, a condition signaled by chest pain in which there is partial to near-total blockage of the arteries into the heart. Or it could lead to a heart attack, which occurs when there is a sudden blockage of the arteries leading to the heart. Angina can signal an impending heart attack or a heart attack can come suddenly without prior warning. At its worst, coronary artery disease can result in sudden death, with or without a history of angina or previous heart attacks.
Coronary artery disease usually begins as the blood vessels in the body begin to clog up. This condition, known as atherosclerosis, or hardening of the arteries, develops over a long period of time. Usually, it begins when something damages the lining of the arteries of the heart. The damage could be caused by smoking, diabetes, high blood pressure or high cholesterol. When a blood vessel is damaged, the body tries to heal it by sending in macrophages, a class of scavenger cells, to repair the damage. But the macrophages themselves soon become part of the problem.
The macrophages and some of the substances they produce begin to stick to the damaged arteries and clog them up further. This adds to the original damage and signals more macrophages to respond, which only makes things worse. Over the years, cholesterol deposits and scar tissue can block the blood vessels further. Eventually, the blood can no longer flow through your blood vessels as it should, and the heart can become damaged.
DIABETES CORONARY ARTERY DISEASE RISKS
Having diabetes is a major risk factor for coronary artery disease. Even if you just have impaired glucose intolerance, your risk of developing angina and heart attack are higher than that of the general population. If you have diabetes and especially if you have problems controlling your blood glucose levels, you are even more likely to develop coronary artery disease. And the longer you have diabetes, the greater the risk. A person who has had diabetes for 15 to 20 years is 10 times as likely to develop coronary artery disease as a person without diabetes.
Other factors also increase the risk of coronary artery disease. These include a family history of coronary artery disease, high blood pressure, a history of smoking, high cholesterol and high triglyceride levels, advancing age, a sedentary lifestyle and obesity.
ANGINA
Angina is a form of coronary artery disease in which you experience chest pain. In itself, angina is not a life-threatening condition, but it does signal a reduced flow of blood to the heart and should not be ignored. It serves as a warning sign that something more serious may occur. In its mildest, stable form, the pain occurs sporadically and lasts only a short time. But angina can get worse as the arteries become more clogged and precede a more serious, or even fatal, heart attack.
DIABETES CORONARY ARTERY DISEASE SYMPTOMS
Symptoms of coronary artery disease usually begins to appear when 50% to 75% of the blood vessel is blocked and the flow of blood to the heart is slowed. The exact symptoms may depend on which part of the heart is not getting enough blood. Symptoms include pain or pressure in the chest, nausea or pain in the upper abdomen, shortness of breath, weakness or irregular heartbeat. However, some people with diabetes have neuropathy, or damage to the nerves and are unable to feel chest pain even though blood flow may be restricted.
The most common symptom of coronary artery disease is chest pain or pressure. It usually comes on gradually, often while exercising and over a period of 30 seconds to several minutes. The pain can intensify, but often it is mild and just goes away. It can also move to the left arm, shoulder, or armpits or the left side of the neck or jaw. The pain often arises during physical activity and goes away when you stop activity and rest. Emotional stress may also trigger an angina attack. But it can also occur when you are resting and can even awaken you in the middle of the night.
What You Should Do
If symptoms last only a short time (2 to 15 minutes) and do not occur more often or at low activity levels, you may have stable angina. If this is the case, you should tell your doctor, who will probably conduct a series of tests to assess the condition of your heart. If you do indeed have stable angina, heart tests you will show no evidence of permanent damage to the heart.
If the symptoms suddenly get worse or show up when you are not exercising, then you may have unstable angina. This is a sign of more serious heart trouble. When the symptoms of angina get progressively worse, then you may be at risk for a heart attack. Anytime your symptoms get worse, especially if the change is sudden, call your doctor or emergency health care center at once.
Whether you have stable or unstable angina, your doctor will most likely conduct a series of tests to determine the condition of your heart and whether your arteries are significantly blocked. This could involve any of the several diagnostic tests.
Your doctor may perform an electrocardiogram, which can detect an abnormal heart rhythm. This will determine whether a heart attack has occurred in the past or is occurring at the time you have your test. Some people, especially people with diabetic neuropathy, can experience a heart attack and not even realize they are having one. As many as one-third of all heart attacks are clinically silent—the symptoms are not recognized or felt by the patient. An electrocardiogram performed at rest will not detect any arterial blockages that have not caused a heart attack, however.
Most likely, your doctor will also recommend a stress test. This is a test that assesses heart activity before, during and after exercise. You will be asked to walk or jog on a treadmill or peddle an exercise bicycle. You will probably increase the level of exercise in steps until you become fatigued or the electrocardiogram become abnormal. Or the test can run until your heart rate reaches a set maximum limit. If you cannot exercise because of some other condition, such as asthma, emphysema, peripheral vascular disease, or other limiting condition, your doctor may perform a chemical stress test. In these tests, an echocardiogram or nuclear imaging technique is done before and after receiving a drug that increases the work of the heart or that expands the arteries of the heart. This test is similar in accuracy to a physical stress test.
Different kinds of stress tests can be performed using different kinds of techniques to look at the heart before and after exercise. A stress test using an electrocardiogram will tell your doctor whether there are parts of your heart muscle that are not getting enough blood. However, an electrocardiogram stress test is not completely accurate. Only 70% of people who have a blockage will be detected by this test. And of the people who do test positively, only about 70% will actually have a blockage.
Along with the electrocardiogram, your doctor may also perform an echocardiogram before and after you exercise. This is an ultrasonic image of your heart. If you do have a blockage, the echocardiogram will show the area of your heart that is affected, because it will move abnormally when you exercise and immediately after.
Your doctor may also recommend a nuclear imaging test of the heart before and after exercising. With this sort of test, you may be injected with a radioactive tracer that will show the blood flow through your blood vessels and heart. This tells your doctor how many blockages there are and how large they are. The echocardiogram and nuclear imaging stress tests will pick up 90% of the blockages in people tested. About 90% of tests that are positive are due to true blockages.
If your stress tests are positive, that is, they indicate that you have blocked arteries, your doctor may also have you undergo a cardiac catheterization and coronary angiography. This is another test that allows a direct view of the arteries and heart. In this test, you will be given a local anaesthetic and a tube, or catheter, will be inserted into one of your arteries. Usually the catheter is inserted into the groin.
The catheter is then moved along the major arteries into the chest. The doctor is then able to measure the blood pressures in different chambers of your heart. In addition, a special dye can flow through the tubes and into your heart, so your doctor can see how the different parts of your heart and arteries are functioning, how the blood is flowing and if there are any blockages in the arteries.
Taken together, the electrocardiogram and imaging stress tests and the catheterization and angiography can give your doctor a good idea of whether or not you have arterial blockages and coronary artery disease. This will help your doctor determine the best way to treat your condition.
DIABETES CORONARY ARTERY DISEASE TREATMENT
Medication
If your doctor determines that you have coronary artery disease, you may be prescribed any of several medications to help your blood flow better and reduce your symptoms. You may be given nitroglycerin or a similar medication. This medicine can be taken under the tongue or through a skin patch or ointment on the skin. It works by lowering the blood pressures of the heart and dilating the arteries to help balance the supply and demand of oxygen throughout the body.
Nitroglycerin and similar drugs can only be used 12 to 14 hours a day, however. If they are used continuously, the body stops responding to them. Side effects include headaches and light-headedness. Although nitroglycerin is effective at reducing angina (chest pain), there is no evidence that it actually helps you live longer.
Another type of medication you may be prescribed is known as beta-blocker. Propranolol (Inderal), atenolol (Tenormin) and metopropol (Lopressor) are all beta-blockers. These drugs reduce the symptoms of angina by lowering the heart rate and blood pressure, reducing the effect of epinephrine on the heart, and by preventing irregular heartbeats.
Beta-blockers have some side effects, however. People with type 1 diabetes who have a history of hypoglycemia have to be especially careful. The drugs can interfere with how the body detects and responds to the warning signs of low glucose. If you have frequent bouts of hypoglycemia and are prescribed a beta-blocker, it is essential that you check your blood glucose level often.
People with type 1 or type 2 diabetes often find that beta-blockers upset their blood glucose control. Even if you are not prone to hypoglycemia, you will probably need to monitor your blood glucose levels more frequently, especially as you are getting used to the new medication.
Beta-blockers may also raise triglyceride levels and lower high-density lipoprotein (HDL, “good cholesterol”) in the blood. If you have peripheral vascular disease, you may find that the symptoms worsen when you are on beta-blockers. If you have asthma or any kind of lung disease, you may be advised not to take a beta-blocker because it can increase the wheezing and make breathing more difficult. If you already have a slow heart rate, you may be advised not to take a beta-blocker, because it may make your heart rate too slow.
Calcium channel blockers work by lowering blood pressure and dilating coronary arteries. Some of these drugs also lower your heart rate. Some types of calcium channel blockers can be used safely by people with diabetes and some cannot. Your doctor will help select the correct medication.
Surgery
There are two types of surgical interventions you and your doctor will want to consider. Angioplasty is a technique that opens up blocked arteries. Cardiac revascularization, or bypass surgery, is a technique using blood vessel grafts that form a detour to move the blood flow around a blocked artery. In the long run, people with diabetes seem to fare better with bypass surgery.
Two types of angioplasty are in common use. With balloon angioplasty, a small balloon is attached to a catheter and inserted into a narrowed artery. Once in the blocked artery, the balloon is inflated, thus compressing the cholesterol plaque and opening up the artery. In many cases, a stent is used in conjunction with a balloon angioplasty. This is a small metal spring or mesh cylinder that is placed at the site of the obstruction to keep cholesterol deposits from closing up the artery again.
Alternatively, a blood vessel can be opened up with rotoblator, which works much like a small drill to bore through the blocked artery. An atherectomy device can actually remove some of the cholesterol plaque. Stents are often used with both rotoblator and atherectomy devices.
Angioplasty is not usually recommended for people with diabetes because of the narrow openings in the arteries, which make it technically difficult to perform. Also, it often results in a small tear in the blood vessel lining that can cause a clot to form. This increases the likelihood of the vessel closing up again and provoking a heart attack.
If you have diabetes, you may have better success with a bypass operation. In this procedure, a blood vessel is removed from your leg or chest and used to bypass the arterial blockage. The new blood vessel is first attached to the artery below the blockage and then to the artery above the blockage. The surgery typically lasts 4 to 6 hours or even longer.
Complications include heart attack, bleeding, infection of the sternum and infection at the site of the vein removal. Complications are more common in people with diabetes, but most survive with excellent results. The decision of whether to proceed with angioplasty or bypass surgery will be made by you and your doctor based on several factors. Much will depend on the size of the opening in your artery, where the blockage is, whether the blockage contains any calcification and whether your heart function is otherwise normal.
DIABETES CORONARY ARTERY DISEASE PREVENTION
Your best bet is to take steps to keep coronary artery disease from developing in the first place or keep it from getting works. This is especially true if you have diabetes and even more so if you have already had a heart attack. Coronary artery disease, angina and heart attack occur because there is a buildup of cholesterol-containing plaque along the walls of the arteries that lead to the heart.
To avoid coronary artery disease, you need to prevent or minimize this buildup from occurring. If you have cholesterol deposits, then your cholesterol levels are too high and you need to take steps to reduce them. You can do this by changing your diet, reducing your weight, exercising more and by taking cholesterol-lowering medication.
Other factors also increase the risk of coronary artery disease and heart attack. You can minimize the contribution of these factors by taking steps to lower your blood pressure, lose weight and stop smoking. Quitting smoking is one of the most effective measures of reducing the risk of heart attack. But it is not easy. If you are having problems quitting smoking, talk to your doctor about your medical and psychosocial interventions that may work for you.
Your doctor may also recommend taking aspirin on a daily basis to reduce the risks of coronary artery disease. This has been shown to reduce the risk of heart attack and stroke by thinning the blood and preventing clotting.
Studies have also shown that a diet rich in antioxidants—vitamins A, C and E—may help prevent artery disease. Consider adding more fruits and vegetables, especially those with deep colors, to your diet. Carrots, sweet potatoes, tomatoes, spinach, broccoli, cantaloupe, pumpkin, apricots, and citrus fruits are all good choices. Vitamin E can also be found in vegetable oils, green and leafy vegetables, wheat germ, whole-grain products, nuts and seeds.
In addition to all these measures, it is important to control your blood glucose levels, whether you have type 1 or type 2 diabetes. Scientists are continuing to study the connection between blood glucose control and cardiovascular disease.
To learn more about the effects of diabetes on your mind and body, visit our diabetes section for more resources. And to discover if your body is already showing signs of diabetes, check out our diabetes symptoms checker.
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Sources and References
The Diabetes Problem Solver—Quick Answers to Your Questions About Treatment and Self-Care by Nancy Touchette
Coronary Artery Disease by Peter McCullough
Coronary Artery Disease and Type 2 Diabetes Mellitus by Ryo Naito and Katsumi Miyauchi
Mixed Angina Pectoris by A Maseri, S Chierchia and J C Kaski
Rich Health Editorial Team
Rich Health Editorial Team is made up of medical practitioners and experienced writers who provide information for dealing with health issues in a simple and easy-to-understand manner
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