Low Muscle Mass Associated With Type 2 Diabetes Risk

The occurrence of insulin resistance, which leads to development of type 2 diabetes, is on the rise. Low muscle mass is known to increase this risk. The present study analyzes the role of this relationship in diabetes management. The possibility of improved glucose metabolism and sensitivity by improving muscle mass was worked out in this study. Interestingly, every 10 percent increment in the skeletal muscle index corresponded with 11 percent relative fall in insulin resistance and 12 percent dip in diabetes prevalence. A stronger relationship was noted in the nondiabetic population.

The recent upsurge in the global occurrence of diabetes has necessitated the identification and addressing of contributive factors in terms of healthcare and economy. Sarcopenia or low muscle mass has been proven to have a negative effect on insulin resistance and therefore, diabetes. The aim of this study was to estimate whether the reverse was true — whether increase in muscle mass above the sarcopenic range would improve glucose sensitivity and therefore, guard against diabetes. This association is even more pertinent in view of the fact that the principal tissue involved in glucose breakdown is the muscle. This study examined skeletal mass index as a fraction of the total body weight.

* This study included 13,644 participants of the Third National Health and Nutrition Examination Survey (NHANES III) with an average age of 41 years.
* Homeostasis model assessment of insulin resistance (HOMA-IR), HbA1C, serum insulin, and fasting blood glucose values for confirmation of diabetes, bioelectrical impedance to calculate muscle mass, body height, weight, and waist circumference were all measured.
* Statistical analysis was carried out to estimate the relation between muscle mass index (MMI) and insulin resistance.

Results/Key findings
* Insulin resistance, blood glucose level, as well as diabetes prevalence decreased linearly with increase in MMI.
* The highest noticeable decrease was with diabetes prevalence reducing by 63 percent, especially from 14.5 percent in the least MMI group to only 5.3 percent in the group with high MMI.
* This association was more pronounced in the analysis excluding diabetics, where for every 10 percent rise in MMI, the insulin resistance reduced by 14 percent and diabetes prevalence by 23 percent.

Next steps/Shortcomings
The cross-sectional design restricts assigning causes. Bioimpedance, being a measure of body water content, shows exaggerated values in patients with renal failure. Due to non-inclusion of ß-cell function in this study, no effective differentiation between type 1 and 2 diabetes was made. The insulin resistance of adipose tissue is likely to have contributed to the result, because people with high muscle mass usually have low fat mass.

This study’s finding of an inverse association between skeletal muscle mass and insulin resistance was applicable across a range of muscle mass distribution. In other words, just increasing muscle mass a little above the sarcopenic extreme influences glucose metabolism to significantly strengthen against insulin resistance and diabetes. This is confirmed by the same effect in nondiabetics. In diabetics, there is also a contribution of ß-cell function on glucose metabolism. Thus, this study establishes the significance of measuring muscle mass along with readings of body mass index (BMI) and waist circumference. This recommends the need for muscle-building exercises in order to avoid metabolic disorders in diabetics, prediabetics, and individuals with risk factors to even prevent the occurrence of diabetes. However, the type and duration of exercises remains to be worked out.

For More Information:
Inverse Association between Relative Muscle Mass and Insulin Resistance
Publication Journal: Journal of Clinical Endocrinology and Metabolism, July 2011
By Preethi Srikanthan, M. D.; Arun S Karlamangla; UCLA David Geffen School of Medicine, Los Angeles, California

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