The latest on managing cardiovascular disease in type 2 diabetics
By William A.Check
Cardiovascular disease (CVD) is one of the most deleterious complications of non-insulin-dependent, or type 2, diabetes mellitus (NIDDM). Half of all patients newly diagnosed with type 2 diabetes have coronary heart disease at the time of diagnosis, and at least 58% die of CVD. In addition, they die earlier, and more die at their first heart attack.
Part of the reason for these serious findings may be that CVD is worse in persons with NIDDM, says Richard Nesto, MD. Dr. Nesto is a clinical cardiologist specializing in the care of diabetic patients with heart disease at Deaconess Hospital in Boston. A substantial number of diabetic patients have silent heart attacks and asymptomatic cardiomyopathy due to diabetes and/or hypertension. For these reasons, the additional left ventricular damage imposed by an acute myocardial infarction (MI) results in a greater degree of congestive heart failure with a higher mortality than in non-diabetics. Also, the platelets in diabetic patients may be partially resistant to aspirin, and optimum strategies of anticoagulation in this setting need to be defined.
Dr. Nesto says some of the higher CVD mortality stems from problems in diagnosing a heart attack in a diabetic patient which may lead to a delay in appropriate treatment. Diabetic patients frequently tell doctors about symptoms that are not interpreted as being coronary in origin.
"I can say that angina or typical chest pain frequently is not the presenting manifestation in a diabetic patient," Dr. Nesto says. "More often they present with shortness of breath, diaphoresis or even difficulty with management of sugar that does not have another explanation."
Not only does this type of presentation fool physicians, it does not warn patients to go to the emergency room. Moreover, studies have detected a higher anginal perceptual threshold in diabetic persons during exercise. Diabetics exercise longer in the face of ischemia before experiencing angina than the non-diabetics. Dr. Nesto suggests that diabetic neuropathy may lead to nerve damage that interrupts transmission of pain impulses from the heart to the brain.
When diabetic persons do go to the hospital, it is often too late to institute thrombolysis. Among patients presenting with their first heart attack in a European thrombolytic trial, diabetic patients who appeared with the same entry criteria as non-diabetic patients received thrombolytic therapy significantly less often (30% vs. 43%). Therefore, diabetic persons must be educated to recognize symptoms that may signal a heart attack.
Also, physicians may be reluctant to institute aggressive therapy when the patient has atypical symptoms. Dr. Nesto advocates using objective criteria such as EKG changes and a rise and fall in enzyme levels.
Medications need to be used carefully in diabetic patients. For example, vasodilators are commonly used, but could lead to light-headedness in some diabetic patients. Beta-blockers have been contraindicated for some diabetic persons, but newer beta-blockers do not have as much effect on glucose intolerance, so diabetic patients can now benefit from the same beta-blocker strategy used for non-diabetic patients--particularly after an MI, Dr. Nesto says.
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