COMPOSITION STUDY

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. RESEARCHDESIGNANDMETHODS — 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 ab-sorptiometry, and muscle strength was measured using isokinetic and isometric dynamometers. RESULTS — Older adults with type 2 diabetes (n 305) showed greater declines in the leg muscle mass (0.29 0.03 vs. 0.23 0.01 kg, P 0.05) and strength (16.5 1.2 vs. 12.4 0.5 Nm, P 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 (1.6 0.2 vs. 1.2 0.1 Nm/kg, P 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 re