Statins Reduce the Risk of Coronary Artery Disease in Type 2 Diabetics

Summarized by Robert W. Griffith, MD
July 2, 2004

Introduction

Type 2 diabetes commonly results in problems affecting the arteries: either the small arteries (affecting the retina, kidneys, and nerves), or the larger arteries (leading to heart attack, stroke, and peripheral vascular disease), or both. To avoid such complications, it's necessary to manage both the blood sugar levels and the known cardiovascular risk factors - which include disturbances of blood lipids.

The American College of Physicians has published guidelines to help internists and primary care physicians manage blood lipid disturbances in type 2 diabetics effectively, and we summarize them here. An important recommendation is that benefit can be expected whether the patient has a raised cholesterol level or not.

What was done

The committee used data from 14 big clinical studies of the use of statins, and related drugs, in type 2 diabetes patients. Eight of the studies were in patients who had established coronary artery disease, and 6 in patients without known coronary disease. The purpose of each study was to determine if the use of a lipid-lowering drug would lower the risk of a major cardiovascular event - death, heart attack, or stroke.

A reduction in risk in the first group of studies (patients who had established coronary heart disease) was termed 'secondary prevention', while risk reduction in patients without cardiac disease was called 'primary prevention'.

Results of the analyses

In the secondary prevention studies, a control patient's risk of having a major cardiac event over an average 4½ year period ranged from 23% to 45%. Treatment with a statin decreased the risk by an average of 7%. It was calculated that 14 patients would need to be treated for 5 years to prevent one such major event.

In the primary prevention studies, the control patients' risk of a major cardiac event was obviously lower - 4% to 19%. Statin therapy reduced this risk by 3%; 35 patients would need to be treated for 5 years to prevent one event.

The LDL cholesterol levels at baseline didn't play a role in the effectiveness of the statin, even when they were below the desirable level of 100 mg/dL (2.6 mmol/L). Moreover, there was no benefit of adjusting the dose to try to reach a particular LDL level.

The recommendations

Based on the results of the analyses, the American College of Physicians made the following recommendations:

1. Lipid-lowering therapy (a statin drug, in most cases) should be given for secondary prevention of a cardiac event, such as stroke or heart attack, to all type 2 diabetic patients with known coronary artery disease.
2. Statins should be given for primary prevention against such events in type 2 diabetic patients who have other cardiovascular risk factors, such as age over 55, high blood pressure, smoking, enlarged left side of the heart, a previous stroke or mini-stroke (TIA, or transient ischemic attack), or peripheral arterial disease.
3. The dose of statins should be at least 'moderate'. The doses used in the studies were:
        atorvastatin 20 mg/day
        fluvastatin 80 mg/day
        lovastatin 40 to 80 mg/day
        pravastatin 40 mg/day
        simvastatin 20 to 40 mg/day.
4. If taking statins, routine monitoring of liver function tests or muscle enzymes is not considered necessary, except if there seems to be a specific problem. At the statin doses used, the rates of elevated liver function tests and muscle enzyme levels were the same in the treatment and the placebo groups.

Comment

The authors of these recommendations state that, overall, lipid-lowering medication leads to a 22% to 24% reduction in major cardiovascular events in patients with type 2 diabetes. This applies equally to people with diabetes whose baseline LDL cholesterol isn't elevated. Doses of statins should be moderate, and are likely to be extremely safe in the majority of patients. Clearly, this report is another 'plus' for statin therapy. Very occasionally, patients will experience a side effect, but these can usually be recognized early, and stopping the drug should reverse the side effect.

Source

• Lipid control in the management of type 2 diabetes mellitus: a clinical practice guideline from the American College of Physicians. V. Snow, MD. Aronson, R. Hornbake,  et al., Ann Intern Med, 2004, vol. 140, pp. 644--649

Related Links
Tight Blood Sugar Control Wards Off Diabetes Complications
How Diabetics Should Avoid Serious Cardiac Events
Walking Is Always Good "Medicine," but Especially for People with Diabetes
Close Attention to Health Goals Benefits People with Diabetes

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