Getting to the heart of diabetes

Move over, blood sugar. In the fight against diabetes, it’s time to focus on managing cholesterol problems and blood pressure, too.

(This article was first printed in the September 2004 issue of the Harvard Heart Letter. For more information or to order, please go to http://www.health.harvard.edu/heart.)

Ever since diabetes was first described more than three thousand years ago by physicians to the pharaohs, blood sugar has been the focal point of this increasingly common disease. That makes sense —diabetes is, after all, the body’s inability to regulate sugar (glucose) in the bloodstream.

People with diabetes are encouraged to measure their blood sugar several times a day. They follow diets that limit the release of sugar into the bloodstream. And most take one or more drugs to help muscle and other cells absorb glucose. These efforts slow the progression of diabetes and help prevent diabetes-related blindness and damage to nerves and blood vessels.

But such steps don’t do all that much to forestall heart disease, stroke, or peripheral artery disease. That’s a big deal, because in people with diabetes, heart attacks and strokes are four times more common, occur earlier in life, and are more likely to be deadly than in people without diabetes. And most people with diabetes — up to 80% — die of heart disease and other circulation-related problems.

This intimate connection between what experts once thought were separate diseases is redefining the concept of diabetes control. Greater attention to two of the “usual suspects” for heart disease — cholesterol and blood pressure — along with continued attention to blood sugar could help people with diabetes live longer and healthier lives.

Programs such as the American Heart Association’s “The Heart of Diabetes” and “Make the link” from the American Diabetes Association and American College of Cardiology have begun playing up the connection between diabetes and heart disease to people with diabetes and their health care providers. The American College of Physicians (ACP), the country’s largest organization of medical specialists, has proposed aggressive new guidelines that spotlight the cardiovascular consequences of diabetes.

Guidelines and programs like these aren’t just window dressing. Surveys show that few people know that diabetes and heart disease go hand in hand. Just as alarming, many doctors don’t either, according to the results of a survey presented at the American Diabetes Association’s annual meeting in June.

“It’s imperative that we broaden the focus from blood sugar alone to blood sugar and important cardiovascular risk factors such as cholesterol problems and high blood pressure,” says Dr. Mark D. Aronson, a professor of medicine at Harvard Medical School.

Controlling cholesterol

Dr. Aronson helped write the ACP’s guidelines on cholesterol control for people with diabetes, published in the April 20, 2004Annals of Internal Medicine. After sifting through hundreds of studies that tested the impact of cholesterol-lowering drugs in people with diabetes, the ACP team concluded that cholesterol-lowering statins cut the chances of having a heart attack or stroke or dying of cardiovascular disease by 22%–24% over just a few years. Use of these drugs would save an extra 3–8 lives per 100 people treated.

Here are the ACP’s main recommendations about cholesterol control for people with diabetes:

• Take a statin if you already have heart disease. You’re in this group if you’ve had a heart attack, experienced chest pain (angina), or ever needed bypass surgery or angioplasty. If you have low levels of both LDL (bad) cholesterol and HDL (good) cholesterol, you might benefit from an HDL-raising drug called gemfibrozil (Lopid) instead.
• Take a statin if you haven’t been diagnosed with cardiovascular disease but have one or more substantial risk factors for it. These include being over age 55, smoking, having high blood pressure or peripheral artery disease, or having had a stroke.

In either case, a moderate dose is probably best. This means at least 20 milligrams per day (mg/d) of Lipitor (atorvastatin), 40 mg/d of Mevacor (lovastatin), 40 mg/d of Pravachol (pravastatin), or 40 mg/d of Zocor (simvastatin). The panel didn’t include recommendations for Crestor (rosuvastatin)because it was so new.

In an interesting break with cholesterol-control recommendations from other groups, the ACP’s guidelines say that statins are so safe that most people don’t need routine blood tests for potential muscle or liver problems.

Checking blood pressure

High blood pressure makes the heart and blood vessels work harder than they should. In people with diabetes, it also contributes to kidney, eye, and nerve damage. Because high blood pressure is especially destructive in people with diabetes, its careful control is more important for overall health than tight blood sugar control.

If you have diabetes:

• Check your blood pressure often, at least every doctor visit. Ideally it should be under 120/80.
• If your systolic pressure (the top number of your blood pressure reading) is above 130, or your diastolic pressure (the bottom number) is above 80, try to get it under 130/80. Lifestyle changes such as exercising more, losing weight, stopping smoking, consuming less sodium or alcohol, or eating a healthier diet (more fruits and vegetables!) can sometimes be enough to do the trick. Many people, though, need one or more drugs to lower blood pressure. The main choices include diuretics, ACE inhibitors, angiotensin-receptor blockers, and beta blockers.

Three bad guys, not one

Make no mistake: Taming blood sugar is an important part of controlling diabetes. It can limit nerve and blood vessel damage, and it may also play a role in preventing heart disease. Paying equal attention to cholesterol and blood pressure, though, will have equally large payoffs.