Diabetic patients are at risk of heart attacks to a greater degree than healthy people. Raised blood cholesterol levels are also a risk factor for heart attacks, and a large study completed recently has reported on the treatment of patients who have already had one heart attack with a drug to lower cholesterol levels, even though cholesterol levels were not raised in these patients. The study summarized here is an analysis of the patients from this study who were diabetic or who had abnormal glucose tolerance.¹

The CARE study enrolled patients in 80 centers in the United States and Canada. They had to have normal cholesterol levels and a previous heart attack (acute myocardial infarction, or MI). They were given either pravastatin -- a "statin" cholesterol-lowering drug -- or placebo, in a random fashion. Over the next five years, the numbers of major cardiovascular events, such as death, nonfatal MI or cardiac surgery, as well as stroke, were counted.

Over 4,000 patients were enrolled in the study. They were asked whether they had been told that they had diabetes, or whether they had been given medication for diabetes. Based on their answers, they were divided into a "diabetes" group and a "non-diabetes" group. About 14% of the patients were diabetic. The non-diabetic patients were then divided into those with a normal fasting glucose level (< 110 mg/dL, or <6.11 mmol/L) or "impaired" glucose tolerance (fasting glucose 110 to 125 mg/dL, or 6.11 to 6.94 mmol/L).

The patients with diabetes were, on the whole, older, female, overweight, and non-white, compared with the non-diabetic patients. They smoked less and drank less alcohol, but were more likely to have had high blood pressure, a stroke or heart failure. Pravastatin produced the same effects on cholesterol levels in the diabetic patients as in the non-diabetic group.

At the end of the 5-year study period, the numbers of cardiovascular events (e.g. death, non-fatal heart attack, or stroke) in the pravastatin-treated diabetic patients were reduced by 25%, compared with the diabetic patients given placebo. A similar beneficial effect was seen in the non-diabetic patients. The number of patients needing surgery (angioplasty, bypass surgery) were less in pravastatin-treated diabetics that in placebo-treated diabetics. Again, a similar effect was seen in the non-diabetic patients.

In the patients with elevated fasting glucose levels but without frank diabetes, the risk of having an adverse cardiovascular event was reduced, although the numbers were too small to allow a definite conclusion about the need to give "statins" to such patients.

These analyses are theoretically open to criticism, as they were mapped out after the study had been completed, rather than being completely designed before the study began. The results, however, correspond with those from a similar analysis from another study of a statin drug in patients with a previous heart attack. It seems sensible, therefore, to treat diabetic patients who have had a heart attack with a statin cholesterol-lowering agent, even if their lipid levels are not abnormal.