Cardiovascular Disease - Long Term Complications: Diabetes

Content provided by the Faculty of the Harvard Medical School

Cardiovascular disease

Three out of four people with diabetes die from a heart disease or stroke. While experts don't fully understand the causal relationship between diabetes and cardiovascular disease, it's clear that diabetes — especially type 2 diabetes — is often accompanied by various heart disease risk factors, such as high blood pressure, high cholesterol, high triglycerides, and obesity. Diabetes is also associated with an increased tendency for forming clots. Kidney disease, a complication of diabetes, also considerably boosts the risk for heart disease. And studies have demonstrated an association between the earliest stage of kidney disease (microalbuminuria) and heart disease. In addition, high blood sugar levels cause glycation (the attachment of glucose to proteins and lipids) and increase the tendency for oxidation. Some scientists suspect that oxidized LDL cholesterol initiates the inflammatory damage that causes atherosclerosis, the buildup of fatty deposits in artery walls. These fatty deposits evolve into plaques that thicken artery walls. When the plaques rupture, immune system cells and platelets (blood cell components that initiate the clotting process) rush to the scene. A blood clot forms, obstructing blood flow.

It can take years for complications to appear, but when they do, they're usually serious. Restricted blood flow to the heart may trigger the chest pain called angina. A critical lack of blood can also cause a heart attack, in which a portion of the heart muscle dies. When blood flow to the brain is blocked, a stroke can occur. A symptom of peripheral vascular disease called intermittent claudication involves pain in leg muscles during exercise. This pain arises from obstructions in the arteries of the legs.

Detecting cardiovascular problems

Heart disease can be prevented and treated. That's why early detection of high cholesterol, high triglycerides, and hypertension is so vital. A fasting blood test can measure levels of LDL, HDL, and total cholesterol, as well as triglyceride levels. Because hypertension usually has no symptoms, it's important to have your blood pressure checked regularly.

If you have any chest pain or pressure, trouble breathing, or lightheadedness, you should be examined for heart disease. Because nerve damage can blunt or change the usual symptoms of angina, people with diabetes must watch for jaw or arm discomfort, dizziness, or shortness of breath after minimal exercise.

Your doctor may recommend an electrocardiogram (EKG), a test of the heart's electrical activity, to check for any abnormalities. A stress test, which monitors EKG changes while you exercise on a treadmill, is even more sensitive. Sometimes it includes an injection of thallium or a heart ultrasound (echocardiogram), which highlight damaged areas of the heart. A more invasive and definitive test for decreased circulation is cardiac catheterization, in which a catheter is threaded through an artery until it reaches the heart. There, a dye is administered that defines any blockages or narrowed blood vessels on an x-ray.

Diagnosing peripheral vascular disease can usually be done with a physical exam and medical history. The pulse in your neck, legs, and feet will be checked for any obstructions. Other tests are sometimes necessary, especially if vascular surgery is an option. Ultrasound is a valuable tool for identifying blockage in the peripheral arteries, the vessels that supply blood to your brain and extremities.

Treating cardiovascular problems

Prevention is the best medicine. For cardiovascular disease, that includes controlling blood glucose levels, eating right, getting regular exercise, quitting smoking, and paying proper attention to your blood pressure, cholesterol, and triglycerides. Also talk to your doctor about whether a daily baby aspirin (81 mg) would help you stave off heart disease.

A number of medications can reduce cholesterol, triglyceride levels, or both, and antihypertensive drugs can keep blood pressure within the normal range. Despite their advantages, many of these medications have side effects, and it's important to make sure that they don't interfere with blood glucose control or mask the symptoms of hypoglycemia. Some commonly used drugs, such as thiazide diuretics, beta blockers, and niacin can affect glucose control.

If heart disease is present, it may be treated with drugs, surgery, or procedures such as balloon angioplasty (in which a balloon is positioned in a narrowed artery and inflated to widen the vessel) and stent placement to keep the artery from closing again.

Exercise, quitting smoking, drugs, balloon angioplasty, and sometimes surgery may relieve leg pain due to peripheral vascular disease. A stroke may require immediate hospitalization. Therapy can include medications, surgery, and rehabilitation, and bypass surgery may be necessary to treat blocked arteries.

It's just as important to follow the preventive measures outlined above after you've had a heart attack or been diagnosed with heart disease. These practices can improve your overall health and lessen the chance that your diabetes will worsen.

Last updated:	January 23, 2007