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April 23, 2008
Insulin Resistance Predicts Heart Disease and Stroke Risk
People with insulin resistance—whereby cells become less sensitive to insulin, the hormone that helps control blood sugar—were more likely to have physical symptoms associated with heart disease and stroke risk than people without insulin resistance, according to a study published in the April 23 issue of AIDS.
Diabetes is a known risk factor for the development of heart disease, and insulin resistance is often a precursor to diabetes. Though no studies have found diabetes to be more common in people living with HIV compared with HIV-negative people, several antiretroviral (ARV) treatments have been associated with insulin resistance and, with it, a potentially higher risk of diabetes.
Insulin resistance has also been found to be associated with cardiovascular disease—which includes heart damage and stroke—in studies involving HIV-negative men and women. To determine if this link also exists among HIV-positive people, Kristen Mondy, MD, of the Washington University School of Medicine in St. Louis, and her colleagues compared the results of metabolic and cardiovascular testing in 50 HIV-positive and 50 HIV-negative patients.
The study volunteers were matched in terms of age and traditional heart disease risk factors. Fifty percent of the patients were African American and 34 percent were women. All of the HIV-positive patients were on ARV therapy, their average CD4 count was 547, and 90 percent had a viral load of less than 50 copies. Cardiovascular risk was determined by looking for endothelial dysfunction— inflammation of the lining of blood vessels—and increased thickness of the carotid artery in the neck, a sign of dangerous blood vessel narrowing caused by a buildup of cholesterol-containing plaque.
Though the HIV-positive patients in general were no more likely than HIV-negative patients to have thickening of the carotid artery or endothelial inflammation, HIV-positive patients diagnosed with insulin resistance were. Another predictor of carotid artery thickness was higher consumption of alcohol, while predictors of endothelial dysfunction were high blood pressure and higher ratio of belly fat compared with limb fat.
Interestingly, none of the ARV treatments taken by the HIV-positive patients were associated with either insulin resistance or heart disease risk, nor was the length of time that people had taken ARV therapy. Mondy’s team concludes with the recommendation that ongoing large cohort studies evaluate the contribution of insulin resistance to cardiovascular disease risk in people living with HIV.
