With recent dramatic increases in obesity worldwide, the prevalence of diabetes, a major source of cardiovascular morbidity, is expected to accelerate. Insulin resistance, which can raise blood glucose levels above the normal range, is a major factor that contributes to the development of diabetes. Previous studies have shown that very low muscle mass is a risk factor for insulin resistance, but until now, no study has examined whether increasing muscle mass to average and above average levels, independent of obesity levels, would lead to improved blood glucose regulation.

"Our findings represent a departure from the usual focus of clinicians, and their patients, on just losing weight to improve metabolic health," said the study's senior author, Preethi Srikanthan, MD, of the University of California, Los Angeles (UCLA). "Instead, this research suggests a role for maintaining fitness and building muscle. This is a welcome message for many overweight patients who experience difficulty in achieving weight loss, as any effort to get moving and keep fit should be seen as laudable and contributing to metabolic change."

In this study, researchers examined the association of skeletal muscle mass with insulin resistance and blood glucose metabolism disorders in a nationally representative sample of 13,644 individuals. Participants were older than 20 years, non-pregnant and weighed more than 35 kg. The study demonstrated that higher muscle mass (relative to body size) is associated with better insulin sensitivity and lower risk of pre- or overt diabetes.

"Our research shows that beyond monitoring changes in waist circumference or BMI, we should also be monitoring muscle mass," Srikanthan concluded. "Further research is needed to determine the nature and duration of exercise interventions required to improve insulin sensitivity and glucose metabolism in at-risk individuals."

Also working on the study was Arun Karlamangla, PhD, MD, of the David Geffen School of Medicine at UCLA.