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The integral relationship between diabetes and coronary heart disease (CHD) has been well established. Statistics vary, but in general diabetic patients have a 2- to 4-fold greater risk for myocardial infarction (MI) or stroke than nondiabetics. There are many risk factors that predispose a diabetic patient to develop CHD, including family history, smoking, obesity, low physical activity, hypertension, and hyperlipidemia. The management of lipid abnormalities is crucial and includes the reduction of low-density lipoprotein (LDL), the reduction of triglycerides, and an elevation in high-density lipoprotein (HDL).
Lowering LDL cholesterol has been shown in many significant clinical trials to reduce macrovascular disease and mortality in patients with type 2 diabetes and remains the primary aim of lipid-lowering therapy. In July of this year, the National Cholesterol Education Program (NCEP) revised the guidelines set forth by the Adult Treatment Panel (ATP III) in 2001. The ATP produced evidence-based recommendations for the management of hyperlipidemia and associated disorders. Since the release of ATP III, there have been 5 large-scale trials using 3-hydroxy-3-methylglutaryl coenzyme A
HMG CoA) reductase inhibitors (more commonly known as statins) that have established clinical end points.
Diabetes is still classified as a high-risk condition by the ATP. The new recommendations address LDL goals for diabetes patients with and without cardiovascular disease (CVD). Diabetic patients with existing CVD are at an extremely high risk for future cardiovascular events, including myocardial infarction (MI) or stroke. The previous guidelines for these patients suggested a minimal target LDL goal of <100 mg/dL. Based on recent evidence, these patients benefit the most from additional reduction in LDL, and therefore the new recommendation is to achieve an LDL goal of <70 mg/dL in this patient population.
For diabetics without established CVD, the recommendations suggest using clinical judgment, based on the presence of other risk factors, to assess the need for lowering LDL below 100 mg/dL. Risk scores can be calculated to determine a patient's 10-year percentage risk of developing CHD. This is a useful tool for clinicians in determining whether additional LDL-lowering therapy is necessary.
The new recommendations by the NCEP do recognize the limitations of the currently available therapies. Even with high-dose statins in combination with other LDL-lowering drugs, total reductions seen in LDL concentrations are typically <50%. Thus, for patients with a high baseline LDL (>150 mg/dL), it may be difficult to achieve an LDL concentration of <70 mg/dL.
It is important to note that ATP III, as well as the American Diabetes Association, still supports therapeutic lifestyle changes (TLCs) as first-line therapy for all diabetic patients, regardless of baseline lipid profiles. In addition, there is now supporting evidence that intensive LDL-lowering therapy with statin drugs will reduce cardiovascular events in diabetic patients. Currently, no goals have been set forth from the NCEP regarding the benefits of raising HDL levels. There has not been enough documentation to date to prove an adequate risk reduction to warrant a change in the current guidelines. New studies are underway, however, so this will be an exciting area to watch in the future.
Community pharmacists play an integral part in the management of hyperlipidemia in diabetes patients. Assessing compliance with lipid-lowering therapies, monitoring for adverse effects, stressing the importance of adherence, and educating patients on their lipid medications are just a few of the essential roles played by community pharmacists.
Dr. Brian is a clinical specialist with Cornerstone Healthcare, High Point, NC.
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