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.

The risk of fragility fractures is increased in patients with either type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM). Although BMD is decreased in T1DM, BMD in T2DM is often normal or even slightly elevated compared with an age-matched control population. However, in both T1DM and T2DM, bone turnover is decreased and the bone material properties and microstructure of bone are altered; the latter particularly so when microvascular complications are present. The pathophysiological mechanisms underlying bone fragility in diabetes mellitus are complex, and include hyperglycaemia, oxidative stress and the accumulation of advanced glycation endproducts that compromise collagen properties, increase marrow adiposity, release inflammatory factors and adipokines from visceral fat, and potentially alter the function of osteocytes. Additional factors including treatment-induced hypoglycaemia, certain antidiabetic medications with a direct effect on bone and mineral metabolism (such as thiazolidinediones), as well as an increased propensity for falls, all contribute to the increased fracture risk in patients with diabetes mellitus.

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

Context Type 2 diabetes is associated with higher bone density (BMD) and, paradoxically, with increased fracture risk. It is not known if low BMD, central to fracture prediction in older adults, identifies fracture risk in diabetic patients. Objective Determine if femoral neck (FN) BMD T-score and FRAX score are associated with fracture in older diabetic adults. Design Three observational studies: Study of Osteoporotic Fractures, Osteoporotic Fractures in Men, and Health, Aging and Body Composition study. Setting Older community-dwelling adults in U.S. Participants 9,449 women; 7,436 men. Main outcome measure(s) Self-reported incident fractures, verified by radiology reports. Results Of 770 diabetic women, 84 experienced a hip and 262 a non-spine fracture during mean (SD) follow-up of 12.6 (5.3) years. Of 1,199 diabetic men, 32 experienced a hip and 133 a non-spine fracture during mean follow-up of 7.9 (2.5) years. Age-adjusted hazard ratios (HR) for one unit decrease in FN BMD T-score in diabetic women were 1.88 (95% confidence interval [CI], 1.43–2.48) for hip and 1.52 (95% CI, 1.31–1.75) for non-spine fracture. HRs in diabetic men were 5.71 (95% CI, 3.42–9.53) for hip and 2.17 (95% CI, 1.75–2.69) for non-spine fracture. FRAX score was also associated with fracture risk in diabetic participants. However, for a given T-score and age or FRAX score, diabetic participants had a higher fracture risk than those without diabetes. For a similar hip fracture risk, diabetic participants had a higher T-score than non-diabetic participants. The difference in T-score was 0.59 (95% CI, 0.31–0.87) for women and 0.38 (95% CI, 0.09–0.66) for men. Conclusions Among older adults with type 2 diabetes, FN BMD T-score and FRAX score were associated with hip and non-spine fracture risk. However, in these patients, compared with participants without diabetes, fracture risk was higher for a given T-score and age or a given FRAX score.