Diabetes is extremely common in the older adult population, affecting more than one-quarter of Americans aged 65 and older. In addition, approximately half of older adults have prediabetes; these are individuals are more likely to develop diabetes in the next few years in the absence of appropriate lifestyle interventions. Thus, three-quarters of the older adult population is either at high-risk for diabetes or already has diabetes.
As people with diabetes live longer, there are many geriatric conditions that occur more frequently in people with diabetes compared to those without diabetes, including cognitive impairment, incontinence, falls, and polypharmacy. Our research in the Women’s Health and Aging Studies has found that diabetes is also linked to frailty (Kalyani et al., 2012; Kalyani et al., 2012). Persons with frailty are much more likely to have diabetes than those who are non-frail or prefrail and they also have dysregulation in hormones of energy metabolism. Previous research has suggested that this relationship is potentially bidirectional: persons with diabetes are more likely to develop frailty, and those who are frail are more likely to develop diabetes. Our studies have also found that higher levels of blood glucose are related to the development of frailty over time, which provides additional insights into potential underlying pathways linking diabetes and frailty.
Physical frailty is defined by unintentional weight loss, low physical activity, exhaustion, slowness, and decreased strength. Emerging data suggest that an accelerated loss of muscle mass, called sarcopenia, may be the key link between diabetes and frailty. Persons with type 2 diabetes (which comprises vast majority of diabetes in older adults) are vulnerable to excessive age-related muscle loss. Although muscle loss can begin in persons with diabetes at younger ages, it occurs more rapidly in older ages, compared to those without diabetes. The loss of skeletal muscle can significantly impact quality of life for people with diabetes and also increase the risk for falls, hospitalization, and mortality.
While diabetes accelerates the process of muscle loss, the mechanisms aren’t fully understood. There are probably multiple mechanisms linking type 2 diabetes and sarcopenia (Kalyani et al., 2014). For example, one of the key roles of insulin is to move glucose from the blood into skeletal muscle tissue where it is necessary for cell function and stimulates protein synthesis. In type 2 diabetes insulin signaling is impaired and insulin is not able to effectively drive glucose into the muscle tissue. This insulin resistance is associated with decreased protein synthesis in the muscle, leading to loss of muscle mass and decreased strength. Insulin resistance is also associated with mitochondrial dysfunction, which results in a decline in skeletal muscle function.
As we celebrate World Diabetes Day this year, we need to recognize that the rapidly increasing number of older adults, and therefore older adults with diabetes, poses a unique challenge to clinicians and researchers. In particular, considerations of the consequences of diabetes beyond the traditional complications such as heart disease and on other morbid conditions such as sarcopenia and frailty, need to be urgently addressed in order to preserve quality of life and reduce mortality for this population.