Main findings of the study
In general, patients with DM2 had inadequate HRQoL, of which the most affected scales were physical function, emotional health, body pain and mental health. Depression was the factor that had the greatest impact on inadequate HRQoL.
This is one of a few recent studies investigating the population with DM2 that included a large number of subjects, in which demographic factors affecting the HRQoL were associated (multivariate analysis); in addition, it did not show that sex affected global HRQoL or physical function, emotional health, body pain and mental health [
16,
28].
The determination that patients with DM2 present low HRQoL coincides with previously published results in which DM2 had a negative impact on QoL, mediated by factors such as the need for a strict dietary plan, exercise and a specific treatment regimen [
29,
30]. The findings in the literature regarding the QoL of patients with DM2 and its association with sociodemographic factors have been variable. Previous reports found that lower educational level, lower income and belonging to the female sex were associated with poor QoL in people with diabetes [
31].
The identified factors impacting QoL, such as older age and depression, impact glycemic control, which could be an added factor that deteriorates QoL [
32]. Another important factor is that patients with DM2 often feel challenged by their illness and the related demands on a daily basis, which also impacts their perception of QoL [
33].
Several studies have shown that the presence of comorbidities decreases the QoL of patients with diabetes; for example, Wermeling et al. evaluated 2086 patients with DM2 in the Netherlands and found that those with comorbidities had a significantly lower health status than those without comorbidities [
34]. In contrast, a study conducted in Singapore failed to find such an association [
35]. Factors such as the time course of diabetes and the use of insulin have also been negatively associated with QoL. In the present study, 85.1% of patients with DM2 presented at least one non-psychiatric medical comorbidity; however, in the multivariate analysis, these comorbidities were not found to impact QoL. Although we did not observe an effect, it is important that health care providers take special care in managing the comorbidities of DM2, as other studies have shown that QoL worsens and that survival drastically decreases as the number of comorbidities increases [
36].
Furthermore, the results of the present study suggest that depression is common among patients with DM2 and is associated with the perception of a poor QoL; depression should be screened for in these patients, especially older patients, who face greater risks related to the lack of motivation and emotional exhaustion [
19,
37].
Depression and diabetes interact so closely that it is difficult to identify which pathology begins first; the diagnosis of DM2 causes mourning for the loss of health, which favors the evolution of depression, and a depressed state can promote poor eating habits [
38]; that is, depression interferes with the ability to initiate healthy life patterns and mitigate risk at the onset of DM2. Emphasis should be placed on the need to better understand any overlap between depression and difficulty in adhering to pharmacological treatment and changes in lifestyle.
The psychological and pharmacological treatment of depression in subjects with diabetes is associated with significant clinical improvements. Such improvements occur not only in mood but also in adherence to diet and treatment regimens for DM2, thereby impacting glycemic control, reducing chronic complications and improving QoL [
38].
The high incidence of elevated depressive symptoms in the sample may be because depressed patients have an increased risk not only for diabetes but also for metabolic syndrome, which is sometimes defined as pre-diabetes [
39]. Therefore, it is possible that there is a bidirectional association between depression and diabetes, i.e., depression can increase the risk for metabolic risk factors that subsequently develop into DM, which increases the risk for mental health status impairment and poor QoL.
Management of DM2 is complicated by psychosocial challenges, and it is important to recognize the potential influence of depression and the deterioration of QoL in the prognosis and management of the disease, as evidenced by the results of this and other studies [
38,
40‐
42]. Additionally, for better control and monitoring of the disease, a combination of effective activities should be implemented to improve self-care [
40].
Consequently, identifying the epidemiological profile and factors associated with QoL in these patients will contribute to the design of a comprehensive program that includes interventions for effective self-care, promotion of the correct use of medicines and promotion of healthy individual and collective conditions.
However, depression is not a DM-specific risk factor for impaired QoL as it is reproducible across different patient populations. Depression was documented as an important predictor of impaired QoL across non-DM patient populations, such as patients with brain tumors and older persons [
43,
44].
One limitation of the study was the type of design, which, being a transversal study, could not identify the relationship between depression and poor perceived QoL, and we could not ascertain which came first. In addition, the study did not analyze QoL according to the presence of chronic complications secondary to DM2.
Depression has an important impact on HRQoL in patients with DM2, and thus, strategies should be developed to prevent depression. It has been shown that exercise on a regular basis, of any type of intensity, prevents depression [
45,
46]. Because of this, some of the strategies should be to promote routine exercise for older adults.