Association between exercise and health-related quality of life and medical resource use in elderly people with diabetes: a cross-sectional population-based study

The world’s population is aging, which affects all fields of societies, including health care system, medical expenditure, labor, finance, demands for goods and services, and family structures [1]. In the United States, elderly population (aged ≥65 years) was 13.7% of the total population in 2012 and projected to be 16.8% in 2020 and 20.3% in 2030 [2]. The prevalence of type 2 diabetes is higher in elderly people. In 2011, > 25% of elderly people have diabetes [3]. Elderly people with diabetes will have substantial microvascular and cardiovascular complications as well as increased risks for frailty, institutionalization, and mortality [3].

Different forms of exercise, including aerobic, resistance, and flexibility, are the cornerstone of diabetic management, especially in elderly people with functional decline [4, 5]. Exercise improves glycemic control, cardiovascular function, muscle strength, and functional capacity in elderly people with diabetes [4, 5]. Exercise is also proved to improve frailty, which is a syndrome associated with increased risks of morbidity and mortality and has higher prevalence in elderly people with diabetes than in those without [4, 5]. Health-related quality of life (HRQoL) and medical resource use are important for elderly health care [6]. Many studies have reported the benefits of exercise for elderly people with diabetes, but the effects on health-related quality of life HRQoL and medical resource use remain unclear. Therefore, we conducted this study to compare HRQoL and medical resource use between elderly people with diabetes with and without exercise.

The male proportion was lowest in the no exercise group (49.7%) and highest in the high-intensity exercise group (72.1%, Table 1). The mean ± standard deviation ages were 73.3 ± 5.2 years, 72.4 ± 4.8 years, 72.5 ± 5.2 years, and 71.5 ± 5.0 years in the no exercise, low-intensity exercise, moderate-intensity exercise, and high-intensity exercise groups, respectively. The non-Hispanic white race was predominant among the four groups. The number of participants who had high school education or less was the highest in the no exercise group (48.1%), whereas the number of those with college degree or higher was the highest in the other three groups. Analyses for marital status showed that the number of married participants was the highest among all groups. Self-report of general health condition as “Excellent/Very good/good” was lowest in the no exercise group (44.3%) and highest in the moderate-intensity (73.7%) and high-intensity exercise (69.3%) groups. The number of participants who had a body mass index of ≥25.0 kg/m² and smoked cigarettes were the highest in the no exercise group. The high-intensity exercise group had the highest number of alcohol drinkers (70.7%). The no exercise group had the highest number of participants diagnosed with hypertension (76.9%) and chest pain (31.3%). The low-intensity exercise group had the highest number of patients with hypercholesterolemia (69.2%) and malignancy (25.6%). The moderate-intensity exercise group had the highest number of participants with coronary heart diseases (17.8%), and the high-intensity exercise group had the highest proportion of individuals with sleep disorders (38.6%).

When comparing HRQoL, the no exercise group had the highest number of participants who were depressed over the last 2 weeks (10.7%) and who had worse health compared with the past year (17.9%, Table 2). The high-intensity exercise group had the highest number of participants who had fever (11.4%), asthma attack (6.4%), and visits to mental health professionals (6.4%) in the past year; however, the differences compared with other groups were not significant.

Comparison of medical resource use showed that the proportion of routine place for healthcare visit was similar among the four groups (Table 3). The no exercise group had the highest proportions of emergency, hospitalization, and total healthcare visits: visited ED most often for healthcare (2.1%), had ≥4 healthcare visits/year (73.7%), were hospitalized overnight in the past year (29.3%), and visited ED for asthma in the past year (1.7%).

Multivariate logistic regression analyses showed that the moderate-intensity exercise group had lower risk for depression over the last 2 weeks than the no exercise group after adjusting for sex, age, race, education, marital status, general health condition, family poverty index ratio, body mass index, cigarette smoking, alcohol drinking, hypertension, cholesterol, chronic heart disease, chest pain, sleep disorders, and cancer (adjusted odds ratio [AOR]: 0.13, 95% CI: 0.02–0.92; Table 4). In the comparison of worse health between the present and past years, the moderate- and high-intensity exercise groups had lower risk than the no exercise group in the crude analysis (odds ratio [OR]: 0.52, 95% CI: 0.28–0.96 and OR: 0.47, 95% CI: 0.26–0.85, respectively). However, the difference lost the significance after adjusting for sex, age, race, education, marital status, general health condition, family poverty index ratio, body mass index, cigarette smoking, alcohol drinking, hypertension, cholesterol, chronic heart disease, chest pain, sleep disorders, and cancer (AOR: 0.83, 95% CI: 0.43–1.58 and AOR: 0.72, 95% CI: 0.38–1.35, respectively). The high-intensity exercise group had higher risk of asthma attack in the past year than the no exercise group (AOR: 2.36, 95% CI: 1.03–5.44). The high-intensity exercise group had a trend for lower risk of overnight hospitalization in the past year than the no exercise group (AOR: 0.65, 95% CI: 0.40–1.04, p = 0.075; Table 5).

The present study showed that male participants with higher education performed more exercise than their counterparts. Participants with moderate- and high-intensity exercise self-reported better general health condition than participants without exercise. Participants without exercise had the highest proportions of being overweight and cigarette smoking. Compared with exercise groups, the number of participants who reported depression over the last 2 weeks and worse health compared with the past year was higher in the no exercise group. In the comparison of medical resource use, participants without exercise had the highest proportions of emergency, hospitalization, and total healthcare visits: visited ED most often for healthcare, had ≥4 healthcare visits/year, were hospitalized overnight in the past year, and visited ED for asthma in the past year. Multivariate logistic regression analyses showed that the moderate-intensity exercise group had significantly lower risk of depression over the last 2 weeks than the no exercise group. The high-intensity exercise group had significantly higher risk of asthma attack in the past year than the no exercise group. Other differences among the four groups were not significant.

The improvements of HRQoL including lower depression in participants with moderate-intensity exercise may be due to better glycemic control, increased muscle strength, increased power and functional capacity, and better cardiovascular function [4]. The mechanisms of better glycemic control by exercise include increases in insulin sensitivity, glucose transporter protein-4 translocation to the muscle cell membrane, glycogen synthase activity, glucose metabolism by increased muscle mass [10, 11], available glucose storage capacity, and glucose clearance from the circulation and reduction in visceral fat [11]. Aerobic and resistance trainings effectively reduced the glycemic levels in individuals with diabetes and even prediabetes [11‐13]. A previous work suggested effective aerobic training including continuous low to moderate-intensity or intermittent high-intensity training 3–5 times per week [4]. Resistance training combining heavy and explosive loads could improve insulin sensitivity and decrease abdominal fat in elderly people with diabetes [11]. The combination of aerobic and resistance trainings is more effective to improve neuromuscular and cardiovascular functions than aerobic or endurance training alone [4]. The level of exercise intensity is also important. Exercise is suggested to be composed of at least 150 min of exercise per week, and more exercise is considered be better, divided into 2 or 3 nonconsecutive days [12]. This study showed that participants with high-intensity exercise had lower depression than those without exercise; however, the difference was not significant. The possible explanation is the limited sample size. We suggest larger studies about this issue in the future.

Elderly people with diabetes have higher risk of depression than those without diabetes [14]. People with depression also have an increased risk of diabetes [15]. Depression contributes to poor compliance of diabetes management, provider–patient communication, and therapeutic effects [16]. In addition, a recent study reported that depression may accelerate cognitive decline in people with diabetes [16]. A systemic review reported that exercise appears to exert beneficial clinical effects on elderly people with depressive symptoms [17]. The guideline of National Institute for Health and Clinical Excellence also suggested structured and supervised exercise programs for people with mild to moderate depression [18].

This study showed that participants without exercise had higher proportions of ED visit, total healthcare visit/year, and overnight hospitalization than the three exercise groups. These findings suggest that lack of exercise may predispose elderly people with diabetes to higher risk for frailty and subsequent complications [4]. The risk of asthma attack in the past year was higher in the high-intensity exercise group than in the no exercise group. Although exercise is a risk factor for asthma attack [19], respiratory exercise program was found to increase muscle strength, patient health, and quality of life [20]. Male participants with higher education performed more exercise, consistent with previous reports [21‐23]. The positive association between higher education and more exercise suggests that education for exercise and its related benefits is important for promoting health in elderly people with diabetes.

The strength of this study is that it clarified an unclear issue by using population-based data. The limitations are as follows. First, the study adopted a cross-sectional design; as such, we could only figure out that exercise was associated with HRQoL, but the causal relationship could not be inferred. Second, the exercise level, comorbidities, HRQoL, and medical resource use were self-reported and therefore may have subjective bias. Third, the number of participants in the three exercise groups was relatively small. A higher number of participants is warranted for further investigation. Fourth, the result may not be generalized to other nations due to differences in culture, race, and medical resource.

This cross-sectional population-based study showed that exercise was associated with better HRQoL and lack of exercise was associated with higher medical resource use in elderly people with diabetes. Exercises including aerobic and resistance training are suggested for elderly people with diabetes. However, further studies including cohort design and more participants must be conducted to validate the results.