Insulin Resistance Linked to Heart Failure

Condition may be another predictor of heart problems, study finds

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HealthDay Reporter

TUESDAY, July 19, 2005 (HealthDay News) -- A new Swedish study reinforces the link between diabetes and heart failure, spotlighting insulin resistance as a key player.

The study of 1,187 men aged 70 and older found that those with insulin resistance were much more likely to develop congestive heart failure (CHF) than those whose bodies responded properly to insulin.

One-hundred four of the men in the study developed congestive heart failure (CHF) during 8.9 years of follow-up, the researcher said. And "insulin resistance predicted congestive heart failure incidence independently of diabetes and other established risk factors for CHF," the authors wrote.

The study, by researchers at Uppsala University, appears in the July 20 issue of the Journal of the American Medical Association.

Insulin resistance is often a precursor to diabetes. Insulin is a hormone that converts glucose -- blood sugar -- into energy for cells. In some people, however, the tissues stop responding to insulin, leaving the body unable to use glucose properly, according to the American Academy of Family Physicians.

It has been known that obesity increases the risk of congestive heart failure, a potentially fatal condition in which the heart muscle weakens, progressively losing the ability to pump blood, the researchers wrote.

"The previously described association between obesity and subsequent congestive heart failure may be mediated largely by insulin resistance," they said.

The study adds another dimension to the relationship between diabetes and heart failure, said Dr. Adi Mehta, an endocrinologist at the Cleveland Clinic Foundation.

An earlier U.S. study found that 32 percent of older men with heart failure eventually developed diabetes, compared to only 18 percent of men with normal hearts, he said.

The most accepted theory for the link between the two conditions starts with the knowledge that fat cells don't use insulin very well, Mehta said.

"As fat becomes more resistant to insulin, more free fatty acids come into the circulation" [system], he said. "They are an alternative source of energy to glucose for cells. Myocardium [heart tissue] that uses free fatty acids for fuel tends to die at a higher rate."

The new finding "is one more brick in the wall that says we can no longer be as fat as we are," Mehta said. "Several things must be done. One is taking early steps to prevent obesity."

But people who are already obese can limit the adverse effects of added fat, even if they have trouble losing weight, simply by exercising, he said.

"If you can improve physical activity in the obese population, there is a very good possibility that obesity would not be as great a health problem," Mehta said.

More information

To learn more about heart failure, visit the American Heart Association.

SOURCES: Adi Mehta, M.D., endocrinologist, Cleveland Clinic Foundation; July 20, 2005, Journal of the American Medical Association

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