Insulin resistance, prediabetes linked to muscle mass

Srikanthan P. J Clin Endocrinol Metab. 2011;doi:10.1210/jc.2011-0435.

Muscle mass is associated with insulin sensitivity and prediabetes risk, researchers found in a cross-sectional analysis of data from the Third National Health and Nutrition Examination Study. For every 10% increase in skeletal muscle index, there was an 11% reduction in insulin resistance.

“Our findings represent a departure from the usual focus of clinicians, and their patients, on just losing weight to improve metabolic health,” Preethi Srikanthan, MD, of the University of California, Los Angeles, said in a press release. “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.”

Srikanthan and colleagues collected data on 13,644 participants aged 20 years and older from the national study. They measured homeostasis model assessment of insulin resistance (HOMA-IR), HbA1c, prevalence of transitional/pre- or overt diabetes and prevalence of overt diabetes. Their goal was to determine whether increasing muscle mass at average or above average levels was associated with improved glucose regulation.

Reductions in HOMA-IR, HbA1c, prediabetes and diabetes prevalence were observed in the lowest skeletal muscle index to the highest. HbA1c had the smallest effect size: 5.8% relative reduction in geometric mean from lowest to highest skeletal mass index (SMI) quartile (5.49%-5.17%). The most impressive relative reduction was 63% and was observed in diabetes prevalence, which was 14.5% in the lowest SMI quartile and 5.3% in the highest quartile. Also of statistical significance were the reductions in all four outcomes from the third highest quartile to the top quartile of SMI, the researchers wrote.

After adjusting for age, sex, race/ethnicity and generalized and central obesity, associations with HOMA-IR and prediabetes were still observed. Each 10% increase in SMI was associated with an 11% relative reduction in HOMA-IR (95% CI, 6-15) and a 12% relative reduction in prediabetes prevalence (95% CI, 1-21).

In those without diabetes, a stronger association was observed with SMI and HOMA-IR and prediabetes prevalence.

“Further work is required to determine the nature and duration of exercise interventions required to improve insulin sensitivity and glucose metabolism in both high-risk and moderate-risk individuals,” Srikanthan said.

Disclosure: The researchers report no relevant financial disclosures.

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