Blindness, kidney failure and amputations are among the calamities that people may likely associate with uncontrolled diabetes, but the most common serious problem caused by diabetes is heart disease.
People with diabetes develop heart problems earlier than those who don’t have the disease, and they are three times more likely to die of heart disease.
Because the link between the two diseases is so strong, “From the standpoint of preventive medicine, we treat diabetic patients as if they already have coronary disease,” says Joseph Hakas Jr., M.D., a cardiologist with Pinehurst Medical Clinic.
Diabetes affects the heart by contributing to atherosclerosis, the build-up of cholesterol deposits, or plaque, on the inner walls of the coronary arteries. These are the large vessels that supply blood to the heart. If the plaque deposits become so thick that they cut off the flow of blood, a section of the heart can die from lack of oxygen and nutrients. That is called a heart attack.
Olujide Lawal, M.D., of Sandhills Cardiology in Rockingham, says that blood sugar levels that are higher than normal but not high enough to be considered diabetic—a condition known as pre-diabetes— can be harmful to the coronary arteries.
“It begins to affect the heart right from the start, often years before the patient has symptoms or is diagnosed with diabetes,” Dr. Lawal says. “So screening for the pre-diabetic state in people who are at high risk for diabetes is as important as screening for diabetes.”
More than half of Dr. Lawal’s heart patients have diabetes.
“Having type 2 diabetes is considered basically the same as having heart disease, because they are so much a part of each other,” he says.
It isn’t clear exactly how diabetes makes arteries more prone to the build-up of plaque, but it seems to be associated with a change in the chemical make-up of the arteries.
“The arteries aren’t just rigid pipes,” Dr. Hakas says. “They can expand and contract in response to stress and other stimuli. In diabetics, the arteries tend to lose that ability, in large part because of chemical changes in the lining.”
In people who don’t have diabetes, plaque is more likely to accumulate in certain sections of an artery rather than uniformly throughout the vessel. That typically isn’t the case with people with diabetes, says Allen Strunk Jr., D.O., of Pinehurst Cardiology Consultants.
“Diabetic changes are often found throughout the coronary arteries, and plaque formation tends to be diffuse,” he says.
Silent plaque
Diabetes often causes neuropathy, which is a numbing of the nerves in various parts of the body. The nerves that transmit distress signals from the heart to the brain seem to be particularly susceptible to diabetic neuropathy. So people with diabetes and with clogged coronary arteries are less likely to experience the chest discomfort or pain known as angina that otherwise might serve as a warning of an impending heart attack.
“Diabetics have a much higher incidence of silent plaque formation,” says Dr. Strunk. “That is, it doesn’t produce the typical symptoms. Sometimes the first sign of plaque shutting off blood flow in the coronary arteries is an actual heart attack.”
That illustrates the fact that the complications of diabetes don’t just start when diabetes is diagnosed.
“For a minimum of five years before that, the patient’s body hasn’t been handling sugar correctly, and harmful changes are already occurring,” Dr. Hakas says. “The day they are diagnosed with diabetes, they are likely to already have complications like eye problems and heart problems.”
That is part of the reason that the American College of Cardiology recommends that physicians treat diabetic patients who have high cholesterol levels as if they already have coronary artery disease—even if they haven’t been diagnosed with a heart problem.
These patients are typically given a class of drugs called statins, which lower cholesterol levels. Studies have shown that statins not only can keep coronary disease from getting worse, but also can even reduce the size of plaque deposits inside arteries.
“We recommend that people with type 2 diabetes have their cholesterol checked regularly,” Dr. Lawal says. “We tend to be more aggressive in treating diabetic patients with high cholesterol, starting them on cholesterol-lowering medication earlier than non-diabetic patients.” |
Olujide Lawall, M.D.
Allen Strunk, D.O.
Joseph Hakas, M.D.
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Obesity and diabetes
Obesity is a major risk factor for both high cholesterol and type 2 diabetes, which is the most common form of the disease. In fact, a high percentage of people with diabetes are obese.
If they can lose a lot of their excess weight and keep it off, their diabetes is much easier to control, and serious complications—including heart disease—are far less likely.
“The majority of diabetics who have bariatric surgery (for obesity) no longer have to take medications for their diabetes,” Dr. Hakas says.
“A year after the surgery, after they have lost a tremendous amount of weight, they often are not diabetic anymore. So, essentially, type 2 diabetes can be curable with large amounts of weight loss. We think that is going to translate into former diabetics having about the same long-term risk of heart disease as the non-diabetic population.”
If someone has so much blockage in one or more coronary arteries that a heart attack is likely—or has already occurred, the standard treatment for almost any patient is either bypass surgery or an angioplasty to remove the blockage and restore normal blood flow to the heart.
If a patient with diabetes has multiple blockages in an artery, then angioplasty may not be feasible. In such cases, bypass surgery is the preferred treatment. Both angioplasty and bypass surgery are slightly less likely to be successful in patients with diabetes.
According to Dr. Strunk, the medical management of diabetes is critical in order to reduce the need for these procedures or to improve the chance that they will be successful.
“We urge referring physicians to try to achieve as tight a control of the diabetes as they can, with aggressive blood pressure and lipid control,” he says.
According to Dr. Strunk, some of the newer medications are more friendly to the blood vessels, including the coronary arteries, than the older ones were, and they have a tendency to reduce the vascular effects of the diabetes.
“Type 1 diabetics who achieve excellent blood sugar control with insulin pumps or multiple daily injections often will delay vascular complications significantly,” he says. “Unfortunately, some patients are content with maybe one injection a day as long as they stay out of major trouble. But the vascular complications march on, unknown and undetected.”
The absolute worst thing that someone with diabetes can do is smoke. Smoking is bad for everyone, of course, but it is especially dangerous for people with diabetes.
“Diabetes and smoking is a terrible combination,” Dr. Hakas says. “I always tell my diabetic patients that if they smoke, it’s virtually guaranteed that they are going to have a heart attack or a stroke. It’s just a matter of when.”  |
