| In older adults, diabetes is a serious public health problem because of high prevalence as well as its devastating consequences such as functional disability and high mortality. Loss of muscle mass and strength, called sarcopenia, has been considered as a common pathway leading to loss of function and frailty in older adults. We investigated the impact of diabetes on skeletal muscle mass and strength in 3,075 older adults aged 70 to 79, enrolled in the Health, Aging and Body Composition Study. Diabetes was defined not only by self report or medication use, but also by fasting plasma glucose and the result of 75-g oral glucose challenge test. Muscle mass was measured by state of the art techniques such as dual-energy X-ray absorptiometry (DXA) and computed tomography (CT). Muscle strength was assessed quantitatively by isometric and isokinetic dynamometers. Muscle quality was defined as maximal muscle strength per unit muscle mass. In cross-sectional study, we found that muscle strength was significantly lower in men with diabetes and not higher in women with diabetes despite of having greater muscle mass than those without diabetes. Muscle quality was consistently lower in both men and women with diabetes than non-diabetic counterparts in both upper and lower extremities. We also found that longer duration (≥ 6 yrs) and poor glycemic control (A1c > 8.0%) were associated with even lower muscle quality. In longitudinal study, older adults with diabetes showed about 50% greater declines in leg muscle strength compared with those without diabetes. Leg muscle quality also declined more rapidly in older adults with diabetes. Skeletal muscle mass, estimated by DXA, declined more rapidly in older adults with diabetes. Interestingly, loss of muscle mass was more pronounced in undiagnosed diabetes. Thigh muscle area by CT declined two times faster in older women with either diagnosed or undiagnosed diabetes than non-diabetic women. The public health importance of these findings is that diabetes is clearly a risk factor for loss of muscle mass and strength in older adults. We need to develop a strategy to prevent rapid loss of muscle mass and strength in this high risk population. |
