By: Ben Eastman
Cardiovascular disease kills approximately 3,000 Americans each day. While this figure is alarming, people with diabetes have even more reason to be concerned as they are two to four times more likely to develop cardiovascular disease. But take heart; there is good news.
In the recent five-year Scandinavian Simvastatin Survival Study (4S), published in the April 1997 Diabetes Care, major coronary events for people with diabetes were reduced by 55 percent by using the drug simvastatin.
A number of factors contribute to the development of cardiovascular disease. These include: body weight, exercise habits, blood pressure, blood lipid (cholesterol) levels, and whether or not you smoke. Cardiovascular disease is almost always the result of atherosclerosis, a gradual hardening or thickening of the walls of the major arteries.
People with diabetes tend to show signs of heart disease at an earlier age than people without the disease. As a result, “cardiovascular disease is the number one killer of people with diabetes. It is present in 75 percent of diabetes-related deaths,” says Philip E. Cryer, MD, FACP, president of the American Diabetes Association (ADA). He also notes that heart disease accounts for one million hospital admissions annually for people with diabetes.
The increased risk of heart disease for people with diabetes appears to be related to higher levels of glucose in the blood and higher levels of blood lipids. Excess glucose binds to proteins and lipids circulating in the blood and attaches to the walls of the arteries, contributing significantly to the formation of plaque, which in turn limits the flow of oxygenated blood to various body parts.
When these blockages occur in arteries leading to the heart, a myocardial infarction, or heart attack, can result. For people with diabetes, maintaining low cholesterol levels is especially critical for the prevention of cardiovascular disease.
Seventy percent of America’s eight million people with diabetes have high or moderately high cholesterol levels. Furthermore, blood lipid abnormalities appear to be more pronounced in type 2 diabetes due to the decrease in high-density lipoprotein (HDL) _ which removes cholesterol from the bloodstream and delivers it to the liver for the body to use _ and higher levels of triglycerides.
In the Scandinavian Simvastatin Survival Study (4S), the cholesterol-lowering drug simvastatin or a placebo was given to 4,444 subjects with prior coronary heart disease (CHD), 202 of whom had diabetes. Treatment with simvastatin resulted in an improvement in the subjects’ blood lipid profiles and a decrease in cardiovascular events. The reduced risk of CHD was especially strong for people with diabetes.
Simvastatin had a positive effect on blood lipids for the entire study group. It reduced total cholesterol by 27 percent, reduced LDL by 36 percent, reduced triglycerides by 11 percent, and increased HDL by seven percent.
Most promising for people with diabetes is simvastatin’s ability to reduce their risk of heart attack. Major coronary events, including heart attacks, were reduced by 55 percent in people with diabetes taking simvastatin compared to those taking the placebo.
Principal author of the study, Kalevi Pyorala, MD, from the University if Kuopio in Finland, notes that “the benefit in terms of the number of serious heart attacks prevented was more than two times greater in diabetics than in non-diabetics with CHD, because diabetic patients have a higher risk of recurrent heart attacks.”
The 4S study did not differentiate between type I and type 2 diabetes, but reports that “almost all of them presumably had (type 2).” Fifty percent managed their diabetes with diet alone, 39 percent with oral hypoglycemic drugs, and only 12 percent with insulin.
The authors also note that diabetes’ effect on blood lipids tends to be more pronounced in type 2 diabetes. The ADA claims that heart disease appears to affect people with type I and type 2 diabetes in the same way, but because the analysis included predominantly type 2s, further investigation is needed to confirm the benefits for type Is.
Simvastatin has been marketed by Merck & Co. since 1992 under the name of ZocorÂ¨. According to the ADA it is “the first and only cholesterol-lowering drug indicated as an adjunct to diet to save lives and prevent heart attacks in people with heart disease and high cholesterol.”
Simvastatin had no effect on blood sugar levels and was generally well tolerated throughout the study. However, the ADA advises that the people with liver disease or “elevated liver tests,” pregnant women, breast feeding women, and all women of child-bearing age (unless highly unlikely to become pregnant) should not use simvastatin.
A Powerful Tool
For people with diabetes, this is an important and encouraging study. It is the first of its kind to include people with diabetes. Previous studies “excluded people with diabetes because their risk was so high. [The researchers] were afraid people with diabetes would alter the statistical significance of their findings,” explains Priscilla Hollander, MD, PhD, director of the Ruth Collins Diabetes Center at Baylor University.
Hollander adds that the 4S is a “demonstration of a major therapeutic advance. It is the first study with dramatic results presenting an available treatment for heart disease in a group in which it is an incredible problem.”
While the drug is now known to help in the treatment of blood lipid levels and the prevention of coronary events in people with type 2 diabetes, experts stress that other preventative measures should not be neglected. Diet and exercise habits are both effective tools for the prevention of CHD and for maintaining normal blood lipid levels as well. In addition, they have positive effects on weight and glycemic control. But now people with diabetes and their healthcare professionals have one more powerful tool on their side.
Simvastatin is not the only cholesterol lowering drug in this category (coenzyme A reductase inhibitors). Others include: fluvastatin, provastatin, lovastatin, and the most recently marketed, atorvastatin. The 4S did not compare the effects of simvastatin with these similar drugs.