Cholesterol-lowering drugs can help prevent heart attacks in patients with type 2 diabetes

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No effect of statin therapy on silent myocardial ischemia in patients with type 2 diabetes without manifest cardiovascular disease, by E. Beishuizen and colleagues. Diabetes Care 28:1675–1679, 2005.

What is the problem and what is known about it so far?

Coronary artery disease is the leading cause of death for people with type 2 diabetes. High blood glucose levels can cause plaque buildup and deep cuts in the arteries. Plaque is a combination of cholesterol (a waxy, fat-like substance), other fatty materials, calcium, and blood components that stick to the lining of the arteries. The plaque buildup reduces blood flow to the heart but often does not cause any pain. This condition is called silent myocardial ischemia. Because silent ischemia is pain free, it can cause a lot of damage to the arteries and the heart before it is found.

Why did the researchers do this particular study?

Researchers wanted to find a way to see if patients with type 2 diabetes had silent ischemia, and if statins, drugs that lower cholesterol, had an effect on preventing it.

Who was studied?

A total of 250 patients with type 2 diabetes and no history of heart and blood vessel (cardiovascular) disease took part in the study. The participants were between 30 and 80 years old and were living in the Netherlands.

How was the study done?

Some of the patients were given a pill containing statins and some were given a pill that contained no medication (a placebo). Neither the researchers nor the patients knew who was taking the statins. In August of 2001, one of the cholesterol-lowering drugs called cerivastatin was taken off of the market, so the researchers replaced it with another drug called simvastatin. At 3, 6, 12, 18, and 24 months after the study began, each patient fasted for 12 hours before taking a blood test to find their cholesterol levels. Silent ischemia is found using a test that monitors the heart while exercising or a test that measures the resting heart rate. Researchers used this information to see if statins reduced the risk of silent ischemia in people with type 2 diabetes.

What did the researchers find?

This was the first study done to see if statins lowered the risk of silent ischemia in people with type 2 diabetes. Researchers found that the statins did not reduce the patients' chances of having silent ischemia. In both the placebo and the statin groups, about 20% of the patients had silent ischemia. But, the medication did seem to protect patients from having heart attacks. After 2 years, 12 patients in the placebo group had heart attacks compared with only 2 patients taking statins.

What are the limitations of the study?

Changing the patients' statin medications in the middle of the study may have affected the results. Also, researchers found that the test that measured the resting heart rate measurements was not as reliable as the test that measured the heart rate while exercising.

What are the implications for the study?

Even though statins do not help to prevent silent ischemia, they are still useful because they help to keep plaque buildup from causing heart attacks. More research needs to be done to find ways to detect and prevent silent ischemia earlier, but it is clear that statins can help people with type 2 diabetes to reduce the risk of heart attacks by maintaining healthy cholesterol levels.

FOR MORE INFORMATION

Drug Therapy for High Cholesterol

Diabetes: A Practical Guide to Managing Your Health, by Rosemary Walker and Jill Rodgers (Alexandria, Va., ADA, 2005)

Adherence to statin therapy and LDL cholesterol goal attainment by patients with diabetes and dyslipidemia, by E.S. Parris and colleagues. Diabetes Care 28:595–599, 2005