Across the full range, higher muscle mass (relative to body size) is associated with better insulin sensitivity and lower risk of PDM. Further research is needed to examine the effect of appropriate exercise interventions designed to increase muscle mass on incidence of diabetes.

BackgroundSarcopenia often co-exists with obesity, and may have additive effects on insulin resistance. Sarcopenic obese individuals could be at increased risk for type 2 diabetes. We performed a study to determine whether sarcopenia is associated with impairment in insulin sensitivity and glucose homeostasis in obese and non-obese individuals.MethodologyWe performed a cross-sectional analysis of National Health and Nutrition Examination Survey III data utilizing subjects of 20 years or older, non-pregnant (N = 14,528). Sarcopenia was identified from bioelectrical impedance measurement of muscle mass. Obesity was identified from body mass index. Outcomes were homeostasis model assessment of insulin resistance (HOMA IR), glycosylated hemoglobin level (HbA1C), and prevalence of pre-diabetes (6.0≤ HbA1C<6.5 and not on medication) and type 2 diabetes. Covariates in multiple regression were age, educational level, ethnicity and sex.Principal FindingsSarcopenia was associated with insulin resistance in non-obese (HOMA IR ratio 1.39, 95% confidence interval (CI) 1.26 to 1.52) and obese individuals (HOMA-IR ratio 1.16, 95% CI 1.12 to 1.18). Sarcopenia was associated with dysglycemia in obese individuals (HbA1C ratio 1.021, 95% CI 1.011 to 1.043) but not in non-obese individuals. Associations were stronger in those under 60 years of age. We acknowledge that the cross-sectional study design limits our ability to draw causal inferences.ConclusionsSarcopenia, independent of obesity, is associated with adverse glucose metabolism, and the association is strongest in individuals under 60 years of age, which suggests that low muscle mass may be an early predictor of diabetes susceptibility. Given the increasing prevalence of obesity, further research is urgently needed to develop interventions to prevent sarcopenic obesity and its metabolic consequences.

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Purpose Obesity (as defined by body mass index) hasn’t been consistently associated with higher mortality in older adults. However, total body mass includes fat and muscle which have different metabolic effects. This study was designed to test the hypothesis that greater muscle mass in older adults will be associated with lower all-cause mortality. Methods All-cause mortality was analyzed by the year 2004 in 3,659 participants from the National Health and Nutrition Examination Survey III, who were 55 years (65 years if women) or older at the time of the survey (1988–94). I ndividuals who were underweight or died in the first 2 years of follow-up, were excluded so as to remove frail elders from the sample. Skeletal muscle mass was measured using bioelectrical impedance and muscle mass index was defined as muscle mass divided by height squared. Modified Poisson regression and proportional hazards regression were used to examine the relationship of muscle mass index with all-cause mortality risk and rate respectively, adjusted for central obesity (waist hip ratio)and other significant covariates. Results In adjusted analyses, total mortality was significantly lower in the fourth quartile of muscle mass index compared to the first: adjusted risk ratio 0.81 (95% confidence interval 0.71 – 0.91) and adjusted hazard ratio 0.80 (95% confidence interval 0.66 – 0.97). Conclusions This study demonstrates the survival predication ability of relative muscle mass and highlights the need to look beyond total body mass in assessing the health of older adults.

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