Insulin resistance linked to peripheral artery disease

Researchers at Brigham and Women’s Hospital (BWH) have shown for the first time that a strong association exists between insulin resistance and peripheral arterial disease (PAD), a risk factor for heart attacks and stroke.  These findings were published in the June 17, 2008 issue of Circulation.

“PAD becomes more common as one gets older, and by age 65, about 12 to 20 percent of the population has it.  Diagnosis is critical, as people with PAD have four-to-five times higher risk of heart attack or stroke,” said Reena L. Pande, M.D., lead author of the study and a physician and researcher in the Cardiovascular Division of BWH.

PAD occurs when arteries in the legs become narrowed or clogged with fatty deposits, reducing blood flow to the legs.  PAD affects about 8 million Americans and is associated with significant disease and death, according to the American Heart Association.  Insulin resistance contributes significantly to the development of diabetes, a known risk factor for PAD, and has been implicated in the development of atherosclerosis; however, the role of insulin resistance in PAD is not well established, according to the researchers.

Pande and colleagues analysed data from 3,242 adults enrolled in the National Health and Nutrition Examination Survey 1999–2004.  The nationally representative sample population study included data on arterial pressure in each person’s ankle.  Comparing the ankle and arm pressures (the ankle brachial index) can indicate restricted blood flow or PAD.  Blood levels of c-reactive protein (CRP) and fasting insulin and glucose were also measured.  Researchers compared PAD incidence and insulin sensitivity using a model of insulin resistance (HOMA-IR), a simple test derived from fasting glucose and insulin values.

The researchers found that people with the highest levels of insulin resistance had twice as much PAD, regardless of other cardiovascular risk factors, including diabetes.  Patients with the highest insulin resistance had nearly twice as much PAD.   The association was still seen after adjusting for age, gender, race/ethnicity, hypertension, hyperlipidemia, smoking, body mass index, chronic kidney disease and CRP.

(Source: Circulation: Brigham and Women’s Hospital: August 2008)