The research team said that insulin resistance -- an impaired response to the presence of insulin -- is detectable as early as 20 years before the symptoms of diabetes become evident. In fact, insulin resistance is now seen as the best predictor that type 2 diabetes will eventually develop, said the study's senior author, Gerald I. Shulman, a Howard Hughes Medical Institute investigator at the Yale University School of Medicine.
In the new study examining how insulin interacts with the energy-producing mitochondria inside living cells, Shulman and his colleagues found that the rate of insulin-stimulated energy production by mitochondria is significantly reduced in the muscles of lean, healthy young adults who have already developed insulin resistance and who are at increased risk of developing diabetes later in life.
"This is further evidence that people who are prone to develop diabetes have signs of mitochondrial dysfunction," Shulman said in an interview. This is important because mitochondria are the "energy factories" inside cells and produce most of the chemical power needed to sustain life.
The new research, which is published in the September 2005 issue of the open-access journal PLoS Medicine, indicates that a decreased ability to burn sugars and fats efficiently is an early and central part of the diabetes problem. Their new data also suggest the basic defect lies within the mitochondria, which exist in almost every cell.
The young adults studied by the research team are the offspring of parents who have type 2 diabetes, adding support to the idea that the risk can be inherited, and that the problem begins well before diabetes symptoms become evident. I
Contact: Jim Keeley
Howard Hughes Medical Institute