Higher good cholesterol cuts heart attack, stroke in diabetic study

Kathleen Blanchard's picture
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Keeping good cholesterol levels higher can cut the risk of heart attack and stroke, found in study that included high risk diabetics.

Findings from a new observational study shows diabetics who raised their levels of high density lipoprotein levels (HDL) had fewer heart attacks and stroke compared to those whose HDL cholesterol levels decreased.

In their study, researchers looked at medical records of more than 30,000 patients with diabetes who have an 87 percent higher lifetime risk of having a heart attack or stroke compared to people who are not diabetic, according to results of the Framingham heart study published in 2008.

Keeping bad or LDL cholesterol levels lower is known to reduce the chances of cardiovascular disease, but whether raising good cholesterol levels can prevent heart attack and stroke has been less clear.

Patients included in the study were diabetic and were entered in Kaiser Permanente diabetes registries in Oregon, Washington and Georgia between 2001 and 2006. A total of 30,067 patients were included.

In 27 percent of the patients, good HDL cholesterol levels increased during the study period. Levels were measured twice, at 6 and 24 months. In 61 percent HDL levels remained the same.

Average increase in HDL levels was 6.5 mg/dl. In 17 percent, good cholesterol levels dropped by the same amount. There were 11 percent more heart attacks in diabetic patients whose high density lipoprotein levels decreased.

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Diabetics who raised their HDL levels had 8 percent fewer heart attacks and stroke, compared to those whose levels remained the same.

Because the study was observational, no specific therapy was used to raise good cholesterol levels. Many of the patients were taking anti-cholesterol medications known as statins to lower so called bad LDL cholesterol levels.

"Our study adds to the growing body of evidence that raising HDL levels may be an important strategy for reducing heart attack risk," said study lead author Gregory Nichols, PhD, senior investigator with the Kaiser Permanente Center for Health Research in Portland, Oregon.

Raising good HDL cholesterol levels can be accomplished with smoking cessation, exercise, maintaining a healthy weight and consuming a diet rich in fruits, vegetables and low in saturated fat.

Medications to raise HDL cholesterol – in particular the B vitamin Niacin – are controversial. Trials of the drug failed to show lower risk of heart attack for patients enrolled in a clinical trial earlier this year. The National Institutes of Health halted the clinical trial.

HDL cholesterol removes "bad" LDL cholesterol; more is better

HDL cholesterol levels of 50 mg/dl of HDL for women and 40 mg/dl for men are desirable according to the American Diabetes Association. Higher good cholesterol levels – 60mg/dl or above – can thwart heart disease. Good cholesterol is thought to remove low density lipoproteins or LDL from the arteries where they can form plaques and block blood flow, leading to stroke and heart attack.

The study, published in The American Journal of Cardiology, adds valuable information that raising HDL cholesterol levels may be important for stroke and heart attack prevention. Keeping LDL levels less than 100mg/dl is optimal for cardiovascular health, according to the American Heart Association.

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