Although the loss of muscle mass is associated with the decline in strength in older adults, this strength decline is much more rapid than the concomitant loss of muscle mass, suggesting a decline in muscle quality. Moreover, maintaining or gaining muscle mass does not prevent aging-associated declines in muscle strength.

Loss of leg MT in older adults is greater than muscle CSA loss, which suggests a decrease in MQ. Additionally, aging is associated with an increase in IMF regardless of changes in weight or SF.

Adequate skeletal muscle strength is essential for physical functioning and low muscle strength is a predictor of physical limitations. Older adults with diabetes have a twoto threefold increased risk of physical disability. However, muscle strength has never been investigated with regard to diabetes in a population-based study. We evaluated grip and knee extensor strength and muscle mass in 485 older adults with diabetes and 2,133 without diabetes in the Health, Aging, and Body Composition study. Older adults with diabetes had greater arm and leg muscle mass than those without diabetes because they were bigger in body size. Despite this, muscle strength was lower in men with diabetes and not higher in women with diabetes than corresponding counterparts. Muscle quality, defined as muscle strength per unit regional muscle mass, was significantly lower in men and women with diabetes than those without diabetes in both upper and lower extremities. Furthermore, longer duration of diabetes (>6 years) and poor glycemic control (HbA 1c >8.0%) were associated with even poorer muscle quality. In conclusion, diabetes is associated with lower skeletal muscle strength and quality. These characteristics may contribute to the development of physical disability in older adults with diabetes.

OBJECTIVE -It has been shown that adults with either long-standing type 1 or type 2 diabetes had lower skeletal muscle strength than nondiabetic adults in cross-sectional studies. The aim of the study was to investigate longitudinal changes of muscle mass and strength in community-dwelling older adults with and without type 2 diabetes.RESEARCH DESIGN AND METHODS -We examined leg and arm muscle mass and strength at baseline and 3 years later in 1,840 older adults aged 70 -79 years in the Health, Aging, and Body Composition Study. Regional muscle mass was measured by dual energy X-ray absorptiometry, and muscle strength was measured using isokinetic and isometric dynamometers.RESULTS -Older adults with type 2 diabetes (n ϭ 305) showed greater declines in the leg muscle mass (Ϫ0.29 Ϯ 0.03 vs. Ϫ0.23 Ϯ 0.01 kg, P Ͻ 0.05) and strength (Ϫ16.5 Ϯ 1.2 vs. Ϫ12.4 Ϯ 0.5 Nm, P ϭ 0.001) compared with older adults without diabetes. Leg muscle quality, expressed as maximal strength per unit of muscle mass (Newton meters per kilogram), also declined more rapidly in older adults with diabetes (Ϫ1.6 Ϯ 0.2 vs. Ϫ1.2 Ϯ 0.1 Nm/kg, P Ͻ 0.05). Changes in arm muscle strength and quality were not different between those with and without diabetes. Rapid declines in leg muscle strength and quality were attenuated but remained significant after controlling for demographics, body composition, physical activity, combined chronic diseases, interleukin-6, and tumor necrosis factor-␣.CONCLUSIONS -In older adults, type 2 diabetes is associated with accelerated loss of leg muscle strength and quality. Diabetes Care 30

OBJECTIVEA loss of skeletal muscle mass is frequently observed in older adults. The aim of the study was to investigate the impact of type 2 diabetes on the changes in body composition, with particular interest in the skeletal muscle mass.RESEARCH DESIGN AND METHODSWe examined total body composition with dual-energy X-ray absorptiometry annually for 6 years in 2,675 older adults. We also measured mid-thigh muscle cross-sectional area (CSA) with computed tomography in year 1 and year 6. At baseline, 75-g oral glucose challenge tests were performed. Diagnosed diabetes (n = 402, 15.0%) was identified by self-report or use of hypoglycemic agents. Undiagnosed diabetes (n = 226, 8.4%) was defined by fasting plasma glucose (≥7 mmol/l) or 2-h postchallenge plasma glucose (≥11.1 mmol/l). Longitudinal regression models were fit to examine the effect of diabetes on the changes in body composition variables.RESULTSOlder adults with either diagnosed or undiagnosed type 2 diabetes showed excessive loss of appendicular lean mass and trunk fat mass compared with nondiabetic subjects. Thigh muscle CSA declined two times faster in older women with diabetes than their nondiabetic counterparts. These findings remained significant after adjusting for age, sex, race, clinic site, baseline BMI, weight change intention, and actual weight changes over time.CONCLUSIONSType 2 diabetes is associated with excessive loss of skeletal muscle and trunk fat mass in community-dwelling older adults. Older women with type 2 diabetes are at especially high risk for loss of skeletal muscle mass.