July 28, 2011 -- Building muscle mass with resistance training exercise may play a role in lowering the risk of type 2 diabetes, a study shows.
The findings are published in the September issue of the Journal of Clinical Endocrinology and Metabolism.
"It's not just weight that matters, but what proportion of your weight is muscle mass," says study researcher Arun S. Karlamangla, PhD, MD, an associate professor of medicine in the division of geriatrics at the University of California, Los Angeles.
Researchers tapped into data from the National Health and Nutrition Examination Survey III on 13,644 adults who were not pregnant and had a body mass index (BMI) of at least 16.5. The researchers wanted to see how muscle mass affects insulin resistance, a precursor to diabetes.
For each 10% increase in the skeletal muscle index (ratio of muscle mass to total body weight), there is an 11% reduction in insulin resistance and a 12% reduction in prediabetes. Prediabetes is a condition in which a person's blood sugar is higher than normal, but not high enough to be diabetes. These relationships held even after the researchers took into account other factors affecting risk for insulin resistance and/or pre-diabetes.
"If you start an exercise program, and don't lose weight, you should not give up hope because your fat is getting converted to muscle," Karlamangla says. "If you lose fat, you gain muscle. So even if the weight is the same, the balance shifts."
Resistance exercise may also have a role in helping people with type 2 diabetes better use the insulin that they do produce, he says.
"It's not too late if you already have type 2," Karlamangla says.