Statins in Diabetes

Summarized by Robert W. Griffith, MD
October 11, 2005 (Reviewed: October 17, 2005)

Introduction

People with type 2 diabetes are at increased risk for having a heart attack (a myocardial infarction, or MI). The reason is that they develop atherosclerosis ¹of the coronary arteries more readily if they have diabetes. Atherosclerosis is associated with deposits of calcium in the plaques that form in the artery wall; this calcification can be viewed by a process called electron beam tomography (EBT) ². It's known that coronary calcification (as measured by EBT) usually progresses at rates between 22% and 52% a year.

Diabetics often have raised triglyceride, total, and LDL (low density lipoprotein) cholesterol, and low levels of HDL-cholesterol (the 'good' cholesterol). These changes unfortunately encourage the development of atherosclerosis. Consequently many of them are treated with statin drugs, to counteract these blood lipid changes.

Now researchers in California have evaluated the progress of calcification in coronary vessels, as a 'marker' for atherosclerosis, in people with type 2 diabetes treated with statins. Their findings are reported in the American Heart Journal, and we summarize them here.

What was done

Type 2 diabetic patients were enrolled in this study as they came to the clinic in Harbor-UCLA, California. There were 120 men and 43 women making up the 163 participants. They had all had an EBT before enrolling in the study, and were willing to have another after an appropriate interval.

All the participants were without symptoms or signs of actual cardiovascular disease. At baseline they provided information on any cardiovascular risk factors they had, such as high blood pressure, high blood lipids, and smoking (and of course diabetes), and their use of statin medication.

Subjects who had a second EBT at least one year after their baseline scan were admitted to the study. All EBT exams were done at the same facility, and were 'scored' for coronary calcification by one physician, who did not know the clinical status of the participant and whether it was a baseline or second scan.

What the results showed

The average age of the 163 participants was 65 - their ages ranged from 41to 90. Only 9 had a zero calcification score at baseline. Their average body mass index (BMI) was 29 and their average HbA1c was 7.8%. The time between EBTs averaged 2.3 years.

Eighty of the subjects (49%) received statin therapy. Overall, the coronary calcification scores increased at a rate of 25% a year. However, the rate in those taking statins only increased at an average of 18% per year, while in those not taking statins it increased 32% a year.

The rate of increase in patients' coronary calcification scores was also slightly dependent on their severity of diabetes - i.e. their HbA1c levels - but to a lesser extent than whether they took statins or not.

What the findings mean

The important finding from this study was that lipid-lowering treatment with a statin resulted in slowing of the atherosclerosis process. In fact, the rate was about cut in half. And this was in patients without any symptoms; they had some risk factors for cardiovascular disease (high blood pressure, high cholesterol, smoking), but, as yet, no symptoms or signs of actual cardiovascular disease.

Diabetic patients have a greatly increased risk for cardiovascular disease. Control of their diabetes, which would be associated with a lowering of HbA1c levels, would help slow the progression of pathology leading up to cardiovascular disease. However, treatment of a cholesterol increase with a statin drug clearly has a greater benefit.

It's questionable as to whether all type 2 diabetics should be given a statin drug, whatever their cholesterol levels. Side effects are normally minimal, although very occasionally they can be severe. Probably it would be better to wait until EBT is available on a wider scale to see which patients really need the statin (although it's obvious that those with raised cholesterol levels should be treated, anyway).

Source

• Diabetes and progression of coronary calcium under the influence of statin therapy. MJ. J Budoff , D. Yu, K. Nasir,  et al., Am Heart , 2005, vol. 149, pp. 695--700

Related Links
Statins Reduce the Risk of Coronary Artery Disease in Type 2 Diabetics
Blood Sugar Predicts Cardiac Mortality
Should We Put Statins in the Drinking Water?

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