Both elevated acylated ghrelin levels and elevated ratios of acylated to nonacylated ghrelin are associated with insulin resistance in overweight or obese postmenopausal women, reported Dr. David H. St-Pierre of the University of Montreal and his associates.
Ghrelin, a peptide derived mainly from the stomach, is an important factor in the regulation of food intake as well as in energy metabolism and storage. Acylated and nonacylated forms of ghrelin appear to induce different physiologic and metabolic effects, but their roles regarding insulin resistance and insulin sensitivity are not well understood, the investigators said (J. Clin. Endocrin. Metab. 2006 Oct. 24 [Epub doi:10.1210/jc.2006–1603]).
Dr. St-Pierre and his associates analyzed ghrelin levels in 89 nondiabetic postmenopausal women who were overweight or obese. They found that insulin-resistant subjects had significantly higher levels of acylated ghrelin and higher ratios of acylated to nonacylated ghrelin, compared with insulin-sensitive subjects, during a test using a euglycemic/hyperinsulinemic clamp.
The results suggest that insulin-resistant women modulate ghrelin in a different way than do insulin-sensitive women. “The sustained elevation of acylated ghrelin circulating levels combined with lower nonacylated ghrelin concentrations might contribute in part to the development of insulin resistance in overweight or obese postmenopausal women,” the researchers said. “A ghrelin profile characterized by higher acylated/nonacylated ghrelin and decreased capacity of maximal reduction may be another indicator of insulin resistance in obese individuals.”