Factors associated with the functional performance of older adults with type 2 Diabetes Mellitus

The aim of this study was to investigated factors associated with the functional impairment of older adult patients with type 2 diabetes mellitus (type 2 DM) and identify the influence of sociodemographic, clinical, and functional factors in this population. This is an observational analytical, and cross-sectional study, which evaluated 159 individuals of both genders, aged 60 years or older. The WHODAS (World Health Organization Disability Assessment Schedule) total score was analyzed in relation to other variables of the study, using the following statistical tests: Mann-Whitney, Kruskal-Wallis, Dunn’s post hoc, Spearman correlation, and simple linear regression analysis. Significance level was set at 5% (p<0.05). In total, 12 linear regression models were generated and the latter was selected for elaborating the prediction equation and its possible interpretations. Functional impairment was associated with sociodemographic, clinical, and functional factors. Sedentary lifestyle, overweight, cognitive deficit, decreased mobility, and falls were the factors that predicted the restriction of functional performance in older adults with type 2 DM. This study assessed the relationship between sociodemographic, clinical, and functional factors concerning the functional impairment of older adults with type 2 DM, reaffirming that this disease causes negative impacts in a global way and that the association among these factors leads to a decrease in functionality and worsening of life quality in this population. The findings of this study point out the importance of preventive programs in order to promote behavioral changes that can reduce the impact of type 2 DM complications.


Introduction
The natural trajectory of type 2 Diabetes Mellitus (type 2 DM) is characterized by being multifactorial, however, insulin resistance and insulin secretion deficiency by β cells are the main factors in the pathogenesis of type 2 DM (Zhao, et al., 2017), which can cause changes in several organs and systems (Kanadani, et al., 2018). Therefore, people diagnosed Although research has shown that type 2 DM is associated with functional deficits, few studies have explored the risk factors (de Rekeneire & Volpato, 2015) and assessed the effect of this chronic disease on the functionality of older adults, which is important because it comprises several domains of life that cover the demands involved in different life activities, like cognition, mobility, self-care, balance, activities of daily living, and participation in society.
Thus, it becomes relevant to assess the conditions that are associated with diminished functionality of these persons. Considering that no studies were found in the literature that have evaluated the functionality of this population through the World Health Organization Disability Assessment Schedule (WHODAS), this study aimed to evaluate the factors associated with functional impairment of older adults with type 2 DM and identify the influence of sociodemographic, clinical, and functional factors in this population.

Study design
This was an exploratory observational, quantitative, analytical, and cross-sectional study (Pereira, et al., 2018), developed in the city of Natal-RN. Initially, 166 older adults were invited to participate in the study, of which 159 (N=159) were selected and 12 were excluded, Research, Society and Development, v. 9, n. 11, e51391110185, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10185 according to the inclusion criteria: 1) age 60 years or older; and 2) diagnosis of type 2 DM, according to the American Diabetes Association (ADA). Exclusion criteria were: presence of physical and cognitive limitations that impeded the performance of tests, such as inability to understand and respond to simple verbal commands and imitate movements; presence of serious cognitive deficit evaluated by Mini-Mental State Examination (MMSE <13 points) (Bertolucci, et al., 1994); severely impaired visual and auditory acuity, which could not be compensated by corrective lenses and sound amplification systems, respectively; and refusing to perform all the tests proposed ( Figure 1).

This study was approved by the Human Research Ethics Committee of the Federal
University of Rio Grande do Norte (UFRN) (Protocol Nº 45185915.9.0000.5537).

Clinical evaluation
The variables analyzed were classified into sociodemographic data (age, gender, educational level, marital status, and marital life), clinical variables, psycho-cognitive aspects Selection of participants: 1) age 60 years or older; and 2) diagnosis of type 2 DM, according to the American Diabetes Association (ADA). (N=166) Eligibility criteria (N=159) Assessment methods (N=159) Research, Society and Development, v. 9, n. 11, e51391110185, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10185 6 (MMSE and Abbreviated Geriatric Depression Scale (GDS-15), and evaluation of functionality. Clinical variables included: subjective perception of health, vision and hearing, height, weight and body mass index (BMI), regular physical activity, number of diagnosed diseases, number of medications used, time of diagnosis of type 2 DM, laboratory tests of the last six months for controlling type 2 DM (fasting glycemia and glycated hemoglobin), use of antidiabetic drugs, presence of lower extremity pain (LEP), occurrence, fear and tendency to fall, and presence of dizziness.

Functional evaluation
Muscle strength was measured by the Hand grip strength test (HSG). This was performed with the SaehanTM palmar grip dynamometer. After adjusting for gender, the mean values found in the three measures were weighed and 37 kg and 21 kg were considered the cutoff points for the male and female older adults, respectively (Sallinen, et al., 2010).
The Timed Up And Go test (TUG) was used to assess mobility (Podsiadlo & Richardson, 1991). A time of 10 seconds or less was considered to indicate older adults who did not present changes of balance nor physical dependencies (Shumway-Cook, et al., 2000).
To evaluate the body balance, the Mini-Balance Evaluation Systems Test (MiniBESTest) was used. This instrument consists of 14 tests, including four domains: 1. Anticipatory postural changes and adjustments; 2. Postural responses to disturbance; 3. Sensory orientation; and 4. Stability in gait. The score ranges from 0 to 28 points and higher scores indicate a better body balance of the individual (Padgett, et al., 2012).
Functional performance was assessed using WHODAS 2.0, a short version of 12 items. The scoring method used was a simple sum, with answers ranging from 0 (no problems) to 4 (very serious problems). The general score for the 12 questions ranges between zero and 48 points, which is then converted to a percentile score (Loke, et al., 2011).
In this study, the highest quartile values (Q75) were considered as indicating a restriction in functional performance.

Statistical analysis
A descriptive analysis was used for the initial presentation of the data. Associations were found between the WHODAS 2.0 total score (dependent variable) and the independent qualitative variables using the Mann-Whitney and Kruskal-Wallis tests. When there was a Research, Society and Development, v. 9, n. 11, e51391110185, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10185 7 significant difference, Dunn's post hoc test was applied in order to identify differences between categories. Correlations were verified between the total score of the dependent variable and the independent quantitative variables, using Spearman correlation (), simple linear regression analysis, and the prediction equation. For all statistical analyses, a significance level of 5% (p <0.05) was adopted.
The majority of the older adults reported having a diagnosis of type 2 DM for more than five years (65.6%), with 66.9% not using insulin to control the disease. The mean of glycated hemoglobin (HbA1c) was 9.3 ± 9.4%, a value considered high according to ADA.
Regarding functionality, the mean in the TUG was 11.5 (4.5) seconds, which is considered within the normal limits for mobility of older adults in this community. The mean of HSG was 29.3 (7.4) kg for males and 18.1 (5.8) kg for females. Values for muscle strength were lower than expected for the different categories and mean of the MiniBESTest was between 22.2 (4.5) and 79.2 (16.2) points, indicating good postural balance.
The interviewees presented an average of 11.0 (8.6) and a median of 10.0 points in the WHODAS 2.0. Of the sample, 58.4% presented scores below the upper quartile, that is, they did not experience a restriction on functional performance. Table 2 shows the significant relationships found in this study.  A total of 12 linear regression models were generated, and the latter was selected. It was verified that physical activity practice, risk of falls, history of falls in the last year, BMI, MMSE, and motor TUG were the significant predictive variables of impairment in functional performance. According to the value of adjusted R, these variables explained 56.2% of the study outcome. Table 3 shows the relationship between variables and functional performance. Research, Society and Development, v. 9, n. 11, e51391110185, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10185

Discussion
This study assessed the relationship between sociodemographic, clinical, and functional factors concerning the functional impairment of older adults with type 2 DM, reaffirming that this disease causes negative impacts in a global way and that the association among these factors leads to a decrease in functionality and worsening of life quality in this population.
Previous studies have shown that older adults with diabetes have two to three times greater risk of developing functional disabilities than non-diabetic individuals due to the occurrence of an accelerated loss of muscle mass (Chau, et al., 2011). Older adults that suffer from mobility deficiency, pain in the lower limbs, history of falls, and dizziness have greater impairment in daily life activities. In addition, those with cognitive decline and depressive symptoms present difficulties in managing medication, using health care services, and dealing with complications (Kim, et al., 2015), which makes it even more difficult to control the disease and practice physical activity, leading to worsening health conditions and functional limitations due to the impact on self-care.
A systematic review (Kan, et al., 2013) suggested that there is a bidirectional association between diabetes and depression. Depression may lead to non-adherence to treatment, poor sleep quality, and decreased metabolism of medications, as well as loss of self-confidence and independence in daily and social life activities, causing isolation in geriatric individuals. These factors can aggravate patients' condition and have been related to an increased risk of falls.
Our results confirm the findings of previous studies revealing that there is a high risk of falls and disability in diabetic older adults (Roman de Metteling, et al., 2013;Kachro, et al., 2015). According to research, this is associated with cognitive impairment due to attention deficit, slowing of the gait speed, and orthotic hypotension. In addition, these individuals present postural balance and gait impairment due to changes in sensory systems and decreased muscle strength, demonstrated in peripheral neuropathy and sarcopenia, respectively (Chiba, et al., 2015).
A meta-analysis indicated that the annual incidence of disability in people with diabetes is about 10% compared with less than 5% in people without diabetes (Wong, et al., 2013). This points to the fact that evaluating the factors that are related to functional impairment in this population is critical to attaining a preventive approach and emphasizes the need for understanding functional incapacity and diabetes, especially in middle-aged and older people. Early diagnosis will allow interventions that are preventive and directed at individuals who are at greater risk (Mendes, et al., 2011).
The evidence found in the present study that functional limitations in older adults with type 2 DM are associated with socio-demographic, clinical, and functional factors needs to be disclosed among health professionals, due to the negative impacts caused globally on these individuals with the consequent impairment in quality of life. These findings highlight the need to prioritize research concerning the factors associated with the appearance of functional deficits in this population, considering that the possibility of intervening in the delay of the onset of disability can reduce the number of dependent older adults.
Finally, it is important to carry out longitudinal studies that more accurately assess the impact of the pathophysiology of type 2 DM on the organs and systems of the body and its consequences on the functional limitations of older adults.

Conclusion
In summary, this study showed that female gender, poor perception of health, no physical activity, use of oral medication and insulin to control the disease, presence of pain in the lower limbs, increased risk of falls, and dizziness were factors associated with the functional impairment in older adults with type 2 DM. Being sedentary, overweight, cognitive deficit, mobility decrease, and falls were factors that predicted restriction related to functional Development, v. 9, n. 11, e51391110185, 2020 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v9i11.10185 12 performance in this population.
Maintaining the functionality of older adults with type 2 DM is assuredly related to a better quality of life. The findings of this study point to the importance of preventive programs in order to provide behavioral changes that can reduce type 2 DM complications.
Clinical trials are suggested to confirm the findings of this observational study.