Obesity and insulin resistance age cells

Science News, June 11, 2005

A person who is overweight and has reduced sensitivity to the hormone insulin may be aging prematurely, according to new research.

Such people develop diseases associated with aging, such as type 2 diabetes and heart disease, earlier than normal. However, the mechanism by which being overweight and having insulin resistance lead to age-related diseases has been unclear.

To see whether obesity and insulin resistance affect aging at the cellular level, Gerald Berenson of the Tulane University School of Medicine in New Orleans and his colleagues examined blood samples drawn at least 10 years apart from participants in the ongoing Bogalusa Heart Study. The focus of the study, which has been running in Bogalusa, La., since 1973, is to identify cardiovascular-disease risk factors over the course of people's lifetimes.

The researchers analyzed white blood cells from 49 study participants. The team measured the length of telomeres on the ends of the chromosomes. These protective caps shrink with each division of a cell, and the length of a cell's telomere is considered a measure of the cell's age.

The telomeres of white blood cells in study participants whose weight and insulin resistance had increased between the times they gave blood samples shortened considerably more than did telomeres of people whose weight and insulin response remained steady, the researchers report in the May 3 Circulation. The finding suggests that obesity and insulin resistance may stress cells and thus accelerate aging, Berenson and his colleagues say.--C.B.