Insulin Resistance Syndrome: Bad for Your Heart
About one out of five American adults suffers from a preventable and reversible condition that puts them at significant risk for heart disease, ]]>stroke]]> , and diabetes. Doctors call it insulin resistance or metabolic syndrome. Many people live for years with no idea they have a problem. But that does not stop damage from occurring. Could you be one of them?
What Is Insulin Resistance Syndrome?
Insulin resistance syndrome is the newest name for a condition that was first noted in the 1980s by Gerald Reaven, MD, at Stanford University. He coined the term Syndrome X. It refers to a clustering of metabolic risk factors for heart disease. Insulin resistance and ]]>obesity]]> are hallmarks of the condition.
“There are grave consequences to overweight,” said Margo Denke, MD, professor of internal medicine at the University of Texas Southwestern Medical Center. “Being overweight starts the clock on metabolic syndrome, which then starts the clock on cardiac disease, diabetes, and stroke. As you gain weight, you have imperceptible increases in multiple risk factors.”
Fat Is Part of the Problem
Overloaded fat cells promote insulin resistance. The tissues become less sensitive to insulin, a hormone cells need to convert sugar to energy. The pancreas, which produces insulin, responds by secreting more of the hormone. This faulty metabolic function leads to other systemic problems, such as abnormal ]]>cholesterol]]> and ]]>triglyceride]]> levels and ]]>high blood pressure]]> as well as inflammatory changes within the blood vessels. This in turn leads to development of atherosclerotic cardiovascular disease.
A Finnish study found a threefold increase in heart disease and stroke in patients with metabolic syndrome. Just how quickly cardiovascular problems develop is subject to debate.
Genetics and a family history of heart disease or diabetes increase the likelihood of developing insulin resistance syndrome (IRS). But that only accounts for part of it. Overeating and a sedentary lifestyle contribute as well.
“The explosion of this syndrome parallels the epidemic of obesity,” said Daniel Einhorn, MD, medical director of the Scripps Whittier Diabetes Institute. Dr. Einhorn co-chaired the American College of Endocrinology’s 2002 conference on IRS.
Experts expect more cases of IRS as the population ages and becomes more diverse. The disease occurs more often in Hispanic, African American, Pacific Islander, and Asian American people. While the risk of IRS increases with age, children also suffer from the syndrome.
Diagnosis of IRS
As awareness of IRS increases, more doctors are diagnosing it. There is no one test to check for IRS. The doctor will ask about your medical and family history and do a physical exam and blood tests. Obesity, in particular, the abdominal type of obesity, is a very significant risk factor.
“The value of knowing you have the IRS is that you can do something about it,” Dr. Einhorn said. “Even with the best in American medical care, most people are diagnosed much too late, after they have heart or other complications.”
Dr. Denke suggests patients not wait for an official medical diagnosis before taking action.
“If you have extra [weight] around your middle, you probably have metabolic syndrome or are heading towards it,” Dr. Denke said. “What’s exciting to me about the metabolic syndrome is that it is a reversible condition—through diet and lifestyle. There is no drug that will reverse it as effectively and rapidly as that.”
Losing at least 5% of body weight and exercising the equivalent of 25 minutes of walking five days a week, can stave off IRS and its adverse effects. Studies show exercise can make the cells more sensitive to insulin. And physical activity burns calories and helps with weight loss.
As for dietary changes, Dr. Denke recommends a low calorie diet. “The main thing is calories, calories, calories. It doesn’t matter where the calories come from.” Insulin sensitivity can improve within a few days of eating less. Some doctors recommend increasing intake of fiber, fruits, and vegetables.
Besides lifestyle changes, doctors can prescribe medications to treat the various conditions related to IRS. If blood pressure is high, patients receive drugs to lower it. Drugs may be ordered to bring cholesterol and blood sugar levels under control.
Researchers hope to develop a direct test for insulin resistance. Others aim to understand more about how the syndrome contributes to heart attacks and how certain aspects of IRS develop. And some doctors are investigating if medications used to treat diabetes could work for IRS.
While much work remains to be done, a consensus exists among experts that lifestyle changes—weight loss and exercise—hold the key to reversing and preventing IRS.
“It’s time to take control of your life and your cardiovascular risk,” Dr. Denke concluded. “We have to start thinking about the consequences to our actions and the lifestyles we have chosen.”
American Association of Clinical Endocrinologists
National Heart, Lung, and Blood Institute
American Heart Association
Findings and recommendations from the American College of Endocrinology conference on the insulin resistance syndrome. Available at: http://www.aace.com/pub/irscc/findings.php . Accessed November 2002.
Ford ES, Giles WH, Dietz WH. Prevalence of the metabolic syndrome among US adults: findings from the third national health and nutrition examination survey. Journal of the American Medical Association . 2002; 287:356-359.
Isomaa B. Cardiovascular morbidity and mortality associated with the metabolic syndrome. Diabetes Care. 2001;24:683-689.
National Cholesterol Education Program, Adult Treatment Panel III Report, National Heart, Lung, and Blood Institute. May 2001.
Rao G. Insulin Resistance Syndrome. American Family Physician. 2001;63:1159-1163.
Vega GL. Results of expert meetings: obesity and cardiovascular disease. American Heart Journal . 2001; 142:1108-1116.
Last reviewed April 2006 by ]]>Marcion Chwistek, MD]]>
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