New research shows that teenagers who are moderately active burn more calories and metabolize blood sugar more efficiently than their sedentary peers - a fact that may protect them from type 2 diabetes.

Type 2 diabetes develops when the body can no longer properly use the blood-sugar regulating hormone insulin, causing blood sugar, or blood “glucose,” levels to soar. The disorder is closely linked to obesity, but studies in adults have shown that regular exercise can prevent or delay its onset.

Whether the same is true of children and teenagers has been unclear.

The question is important because rising rates of childhood obesity are leading to rising rates of type 2 diabetes.

For the new study, reported in the journal Diabetes Care, researchers at the University of Alabama at Birmingham outfitted 32 male and female teenagers with accelerometers - small devices worn on the hip that record the body’s movement throughout the day.

The researchers found that teens who were moderately active over 1 week generally had a higher metabolism at rest than those who were more sedentary. They also had better results on tests of glucose tolerance, a measure of how well the body metabolizes carbohydrates. People with impaired glucose tolerance may go on to develop diabetes.

While the study was short-term, the results suggest that regular exercise could help protect teenagers from both obesity and type 2 diabetes, write Amy S. Thomas and her colleagues.

They also point out that the teenagers in the study got very little vigorous exercise; instead moderate activity, like walking, seemed to improve metabolism.

Further studies, the researchers conclude, are needed to see physical activity translates into lower rates of obesity and diabetes.

SOURCE: Diabetes Care, January 2009.