Adiponectin a Marker of Heart Risk in Diabetics

Researchers have found that circulating levels of adiponectin, a protein hormone produced and secreted exclusively by adipocytes (fat cells) that regulates the metabolism of lipids and glucose, are inversely related to the incidence of cardiovascular disease in patients with type I diabetes (juvenile diabetes).

Adiponectin is a 247 amino acid protein consisting of an N-terminal collagen-like domain and a C-terminal globular domain. The globular domain shares significant homology to the globular domains of type VIII and X collagens, subunits of the complement factor C1q. The 2.1 angstromÅresolution crystal structure of the globular domain of adiponectin reveals significant homology to the TNF (tumor necrosis factor) family. Serum levels of adiponectin are significantly decreased in both obesity and type-2-diabetes, indicating a possible metabolic role or relationship to insulin resistance.

In the current study, investigators at the University of Pittsburgh (PA, USA; www.pitt.edu) determined adiponectin levels in patients selected from the Pittsburgh Epidemiology of Diabetes Complications Study, a 10-year prospective follow-up study of childhood onset type I diabetes mellitus. Twenty-eight diabetes patients with a history of coronary artery disease were tested along with 34 controls that were matched for gender, age, and duration of diabetes.

They reported in the January 2005 issue of Diabetologia that adiponectin levels were significantly higher in women (average of 20.8 micrograms per milliliter) than in men (average of 16.5 micrograms per milliliter). They also found that the higher the adiponectin level, the lower the likelihood that the patient suffered from cardiovascular disease.

"There was a remarkable 63% reduction in risk of coronary artery disease for each 6.3 microgram per milliliter increase in serum adiponectin levels,” said senior author Dr. Trevor Orchard, professor of epidemiology, medicine, and pediatrics at the University of Pittsburgh. "These results are striking despite the relatively small number of patients in the study. Our results--the first to show such a strong predictive power for heart disease prospectively in any population--raise the possibility that adiponectin concentration may prove not only a useful marker of cardiovascular risk, but also a potential therapeutic agent for prevention, particularly among high-risk individuals.”



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