|Year : 2022 | Volume
| Issue : 1 | Page : 35-42
Optimism, Quality of Life, and Psychological Distress in Patients with Type 2 Diabetes Mellitus: A Case–Control Study
Ottilingam Somasundaram Ravindran1, Natarajan Shanmugasundaram1, Saidivya Madhusudhan2
1 Department of Psychiatry, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
2 Department of Clinical Psychology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
|Date of Submission||08-Jun-2021|
|Date of Decision||09-Aug-2021|
|Date of Acceptance||29-Sep-2021|
|Date of Web Publication||05-Jul-2022|
Dr. Ottilingam Somasundaram Ravindran
30 (New No. 17), 23rd Cross Street, Besant Nagar, Chennai - 600 090, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Background: Type 2 diabetes mellitus (T2DM) is a serious chronic illness which has a major impact on the psychological well-being of the individuals. Aim: This case–control study compared the optimism, quality of life (QOL), and psychological distress between T2DM persons and healthy controls and examined the relationship of optimism with QOL and psychological distress among T2DM persons. Materials and Methods: Using a purposive sampling technique, this study was conducted in the General Medicine Outpatient department of a tertiary care hospital between January and March 2020. Fifty participants (25 cases and 25 healthy controls) in the age range of 30–60 years took part in the study. Both groups were assessed by the following instruments: Life Orientation Test-Revised, WHOQOL-BREF, and Depression Anxiety and Stress Scale. Results: T2DM persons are experiencing significant psychological distress with a pessimistic disposition and reduced QOL. Furthermore, optimism was positively correlated with psychological health among T2DM persons. Conclusions: T2DM persons are found to be pessimistic and distressed with significant reductions in their QOL.
Keywords: Diabetes, distress, optimism, quality of life
|How to cite this article:|
Ravindran OS, Shanmugasundaram N, Madhusudhan S. Optimism, Quality of Life, and Psychological Distress in Patients with Type 2 Diabetes Mellitus: A Case–Control Study. Indian J Psy Nsg 2022;19:35-42
|How to cite this URL:|
Ravindran OS, Shanmugasundaram N, Madhusudhan S. Optimism, Quality of Life, and Psychological Distress in Patients with Type 2 Diabetes Mellitus: A Case–Control Study. Indian J Psy Nsg [serial online] 2022 [cited 2022 Aug 20];19:35-42. Available from: https://www.ijpn.in/text.asp?2022/19/1/35/349888
| Introduction|| |
The prevalence of diabetes mellitus has increased significantly over the past two decades. India has the largest number of diabetic population in the world, and it is expected that there will be 69.9 million individuals with diabetes in India by 2025. It is a progressive metabolic disorder affecting every aspect of the patient's life, particularly the physical and psychological well-being.
Depression and anxiety are frequent comorbid conditions in persons with type 2 diabetes mellitus (T2DM). Two meta-analyses report that depression is almost twice as common in T2DM compared to nondiabetic individuals., T2DM persons often report higher levels of depressive symptoms due to both related complications and disease management, leading to required lifestyle changes. Moreover, external factors as employment and marital status, body mass index, body image, smoking habits, and physical activity could predict depression in T2DM. Anxiety disorders are believed to be more prevalent in people who have chronic illnesses compared with healthy people. Anxiety is one of the most prevalent psychiatric problems, particularly among females and low-socioeconomic individuals. Anxiety disorders correlate directly with poor adherence to treatment and increased adrenergic activity. A prior study reported that symptoms of anxiety and depression adversely affect the degree of acceptance of illness and significantly lower the quality of life (QOL) of those with diabetes. Stress has been suspected as having important effects on the development of diabetes through different pathways through behavioral and physiological mechanisms. Behavior-induced emotional stress was associated with lifestyle factors such as dietary behavior, physical inactivity, smoking, and alcohol abuse. On the other hand, physiological stress is associated with long-term activation of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous systems, resulting in chronic stress reactions, including depression, anxiety, and mood disorders.
Diabetes mellitus is a serious chronic illness that imposes significant morbidity and mortality and has a major impact on the QOL of the individuals suffering from this illness. Multiple factors have been shown to modify the QOL in T2DM persons. The most prominent factors include the presence of diabetes distress, use of insulin, medication adherence, longer duration of diabetes, marital status, depressive symptomatology, and comorbidities among others. There have been reports of high incidence of depression and anxiety occurring among persons with T2DM. The presence of these symptoms, especially depression, correlated significantly with a reduced well-being and affected the feeling of positive well-being in T2DM persons. Furthermore, the presence of diabetic complications has an additional negative effect on QOL.
On the other hand, positive psychological characteristics such as optimism may also play an important role in medical outcomes. Optimism is a psychological trait characterized by positive expectations about future that has been associated with better psychological and physical well-being, particularly during times of stress. Optimism is thought to play a protective role in stress-related conditions such as cardiovascular diseases. In line with behavioral self-regulation theory, the way in which people face challenges or difficulties influences how they cope with stress. Having an optimistic point of view increases confidence, motivating individuals to achieve goals as well as increasing positive affect and well-being. Optimism is associated with adaptive coping styles and health-protective behaviors. It has been reported that optimistic patients may have coping strategies characterized by better acceptance of the disease, and this can contribute to a lower risk of certain chronic diseases and, as a result, better QOL. It is worth noting that having a disease such as T2DM has been associated with a lower health-related QOL and psychological distress is common in T2DM persons. Accordingly, optimism is relevant as it may contribute to a better acceptance of living with a chronic disease such as T2DM, translating into greater self-reported QOL. Therefore, studying the relationship between optimism, QOL, and psychological distress in T2DM persons may provide valuable information about the possible protective role of optimism in people living with a chronic disease. Taking into account that optimism is a protective trait, it is plausible that individuals with T2DM who have high levels of optimism could have an enhanced QOL and psychological well-being. Hence, we hypothesize that T2DM persons would be more optimistic, have better QOL, and less psychological distress in relation to healthy controls. Therefore, the present study was undertaken with the following objectives: (a) to compare the optimism, QOL and psychological distress between T2DM persons and healthy controls and (b) to examine the relationship of optimism with QOL and psychological distress among T2DM persons.
| Materials and Methods|| |
A case–control study was done using a convenience sampling. Participants diagnosed with T2DM (n = 25) were recruited from the General Medicine Outpatient department at Sri Ramachandra Institute of Higher Education and Research in Chennai. The study was carried out between the periods of January 2020 and March 2020. Cases were all consecutive patients of T2DM attending General Medicine OPD during the study period. T2DM persons were eligible for selection if they were: (a) aged 30–60 years diagnosed with diabetes according to the American Diabetes Association criteria with an illness duration of minimum 5 years (b) minimum educational qualification of 6th standard. Patients having complications of diabetes (acute or chronic), having an axis one psychiatric diagnosis prior to diabetes, having other physical illnesses, or cognitive impairment that precluded their participation in the study were excluded from the study. We chose one age- and sex-matched control for each case. Controls were recruited from the community who volunteered to participate, and they were ruled out for any chronic medical conditions through history. A prior informed consent was obtained for inclusion in the study, and all participants were informed of the purpose of the study. We obtained approval from the Institutional Ethics Committee of our institution. The study sample was assessed using the following instruments:
Life Orientation Test-Revised
Optimism was assessed with the 10-item Life Orientation Test-Revised (LOT-R) developed by Scheier and Carver. The LOT-R was designed to measure optimism trait that evaluates generalized positive or negative expectancies in life. Participants were asked to indicate the extent of their agreement with each item from 0 (strongly disagree) to 4 (strongly agree). Six items are used to derive the optimism score, and the total score can range from 0 to 24. Higher scores indicate greater optimism, means an optimistic disposition, and the lower scores mean a pessimistic disposition. The remaining four questions on the LOT-R are filler items. The internal consistency for the scale is 0.80.
QOL was assessed with 26-item World Health Organization QOL short version. The items are related to overall QOL and general health. The four domains of the WHOQOL-BREF are physical health (7 items), psychological (6 items), social relationships (3 items), and environment (8 items). Subjects would rate all the items on a 5-point Likert-type scale. The mean score of questions in each domain was used to calculate the domain scores, and finally, they were transformed linearly to a 0–100 scale. Higher scores indicate higher levels of QOL. The Cronbach's alpha coefficient of different domains ranged from 0.76 to 0.88.
Depression Anxiety and Stress Scale
Psychological distress was assessed using the Depression Anxiety and Stress Scale (DASS). The DASS is a 21-item instrument measuring current symptoms of depression, anxiety and stress over the past week. Each of the three scales consists of 7-item in which the participants are expected to rate each of the statement on a four-point scale ranging from 0 to 3. The range of possible scores for each scale is 0–21. The scores for depression, anxiety, and stress are calculated by summing the scores for the relevant items. Internal consistency of the DASS subscales was high with Cronbach's alphas of 0.94, 0.88, and 0.93 for depression, anxiety, and stress, respectively.
All participants who gave written informed consent were interviewed. Their sociodemographic details were collected, and they were assessed using the LOT-R, WHOQOL-BREF, and DASS. All the assessments were done by the third author (MSD). The interview was completed in a single session and lasted 1 h. Data were analyzed using the Statistical Package for Social Sciences for Windows, version 17 (SPSS Inc., Chicago, IL, USA), and P < 0.05 was accepted as statistically significant. Comparisons were made using the Mann–Whitney U-test. The odds ratio (OR) and its 95% confidence intervals (CIs) were calculated. Associations between the different variables were studied using the correlation coefficient.
| Results|| |
The sociodemographic profile of the study group is shown in [Table 1]. Participants' age ranged between 30 and 60 years. The mean age of the participants in both the patient and the control group was 50.60 (standard deviation = 7.17) years. Majority of the participants were females in both cases and control groups (68%). Most of the persons with T2DM were married (92%), had completed high school (68%), have family history of diabetes (64%), unemployed (56%), and 56% of them were in the 51–60 years of age group.
[Table 2] shows the scores obtained by the two groups on the measures of LOT-R, WHOQOL-BREF, and DASS. The Mann–Whitney U-test indicated significant group differences between the diabetic cases and the controls. Comparison of scores for the two groups revealed that persons with T2DM had shown higher levels of pessimism, significant decline in the QOL, and experienced higher levels of depression, anxiety, and stress than the other group.
|Table 2: Comparison of optimism, quality of life and psychological distress between the two groups|
Click here to view
[Table 3] shows that persons with T2DM have the higher risk of developing stress, depression, and anxiety in contrast to the controls.
The relationship between optimism, QOL, and psychological distress (as measured by the LOT-R, WHOQOL-BREF and DASS) among persons with T2DM was examined [Table 4]. Optimism positively correlated with QOL (r = 0.41, P < 0.05) and negatively correlated with psychological distress (r = 0.47, P < 0.05; r = 0.39, P < 0.05).
|Table 4: Correlation between optimism, quality of life and psychological distress|
Click here to view
| Discussion|| |
The purpose of this study was to compare the optimism, QOL, and psychological distress in individuals with T2DM with an equal number of healthy participants and also to examine the relationship of optimism, QOL, and psychological distress among T2DM persons. Results of the current findings show that participants with T2DM are found to be pessimistic, had shown reduced QOL, and experienced higher levels of psychological distress. T2DM persons obtained a score of 15.28 on the LOT-R, which indicated that they are pessimistic and hold beliefs that they hardly ever expect things to go their own way, and they rarely count on good things happening to them. It can be explained that chronically ill patients such as persons with T2DM and healthy people hold similar positive views of the future and of their skills to deal with adversity. Optimistic beliefs play a significant role in adaptation to chronic disease, and they may decrease when people are confronted with repetitive or major adversities. Moreover, depressive symptoms are also relevant in predicting a decrease in optimistic beliefs such as positive outcome expectancies and efficacy expectancies which are assumed to be rather immune to adversity. Optimistic beliefs are threatened by the presence of depressive symptoms and the results of the current study demonstrated that depressive symptoms are quite common among T2DM persons. A prior study found that depressive symptoms were associated with decreased positive outcome expectancies 1 year later in persons with heart disease, although the authors caution that their study does not allow for a causal explanation of the role of depression in optimistic beliefs. In addition, the decrease in optimistic beliefs may be due to the declining socioeconomic situation in the society and the dominance of a pessimistic atmosphere as a result of economic and social problems. Similar findings have been reported by other researchers. In the current study, we found that majority of the T2DM persons (64%) belonged to lower-income group with monthly earnings ranging between Rs. 5000 and 20,000. Environments with lower socioeconomic status can reduce their optimism. In addition to diminishing optimism, it can increase their disappointment and insecurity, which is closely linked to depression. The above findings are in line with findings in previous studies.
T2DM inflicts a significant burden in terms of disability and impaired QOL. Results of the current study suggest that the patient group was impaired in all domains of WHOQOL-BREF than the nondiabetic group. Among the four domains of QOL, persons with T2DM scored highest in the social relationship domain (81.48 ± 19.94) and lowest in the environmental domain (17.84 ± 7.63) in comparison to their counterparts. Results of the current study indicated that, from all the domains, the social relationship domain was the least affected, which is similar to the findings of other researchers. This could be due to the prevalent of social support they received from their families and friends. Previous reports indicated that marital status had a positive association with the social relationship domain. Those who were single were more likely to have a lower QOL compared to the married ones. Results of the current study show that the majority of the T2DM persons were married (92%), and living with their partners shows that the presence of supportive interpersonal relationship has the potential to influence the well-being in T2DM persons. However, the QOL scores were lower for physical health domain (22.90 ± 8.32) which represented physical functions, disability, and needs showed that T2DM persons have lower energy and work capacity for daily living, fatigue, sleep related problems, restlessness, greater pain and discomfort in their daily life. Similar findings have been reported by other researchers. Moreover, the longer disease duration has a negative impact on health-related QOL of T2DM persons. Longer disease duration increases renal, eye, neural and other complications of diabetes and being dependent on medications for a long time which may then contribute to impairment in health-related QOL most notably, the physical health domain. On the domain of psychological health, persons with T2DM scored lower (30.08 ± 12.43) than the nondiabetic group. Lifestyle modifications of diabetes treatment such as adherence to specific dietary guidelines, exercising, monitoring blood glucose level, worry about complications associated with diabetes, and dependence on medications are some reasons for reductions in the QOL. These might cause negative feelings, such as depression, significant reductions in social interactions, and recreational activities causing impairments in the psychological health domain. Similar findings have been reported by previous researchers. T2DM persons have obtained the lowest score in the environmental domain. This could be justified by their dependency on many different medications, the money much needed to afford these drugs, and the demand for the healthcare services are contributing to impairment of the environmental health domain. The above findings are in line with the findings of previous researchers.
Diabetes and its complications are strongly associated with psychological distress. Results of the current findings suggest that persons with T2DM had shown significantly higher levels of depression, anxiety, and stress than the nondiabetic group. A previous research found that the rates of psychological distress are higher in people with T2DM than in the general population. The present study found that the prevalence rate of depression was higher between 30 and 60 years (52% vs. 12%) respectively in cases and controls. Conversely, prior studies among diabetic patients had found higher rates (87%) than our study. The differences in the rates of depression between our study and others may be attributed to differences in the screening or diagnostic tools used, sample size, and behavioral-related factors among study participants. In line with other studies, the results of the current findings indicated that a number of risk factors may increase the likelihood of depression which includes being a female gender, family dysfunction, and experiencing adverse life events. These results concur with those of Larijani et al. who found a higher prevalence rate of depression in the age group of 31–59 years. Many other factors have been implicated for this gender-specific issue such as pregnancy, menstrual cycle changes, postpartum, and other family stressors which could lead to depression.
We found a higher prevalence of anxiety (56%) among T2DM persons, and a prior research also reported a higher prevalence of anxiety among people with chronic diseases such as diabetes. Female sex has been associated with higher rates of anxiety among those suffering from diabetes. A possible explanation is women play many specific roles, which exposes them to increased work demands and responsibilities. Furthermore, the social role attributed to women (passivity, dependence, and emotional expression) allows them to be more emotional and extroversive in nature in comparison to men.
This study showed a higher prevalence rate of stress (60%) among persons with T2DM. A prior Indian study estimated the prevalence of stress to be 39.42% among T2DM persons. Majority of the female respondents with T2DM of this study (68%) identified diabetes to be a major stressor in their lives, but other forms of social stress were even more common. Concern for their children's future was most common, including the stress of arranging a child's marriage and paying for a daughter's dowry. Further, they revealed concerns regarding interpersonal abuse and living with an alcoholic spouse. Similar findings have been reported by other researchers.
The negative correlations observed between optimism and psychological distress are in line with findings in previous studies demonstrating that pessimism exacerbated the psychological distress in T2DM persons. The current findings indicated that participants with T2DM were unrealistically pessimistic about the chance of developing Coronary Heart Disease/Stroke as a consequence of diabetes. There are several possible reasons for the inflated estimation of CHD and stroke in our sample. First, individuals with T2DM are already living with chronic illness. Moreover, chronic illness and disability are concepts that are more cognitively available and hence more salient and accessible. As such, the principle that “if it hasn't happened yet, it won't” which underpins optimistic bias in nondiabetic group, but fails in people with T2DM. Although cardiovascular disease is not perceived as a fearful outcome for most people, for persons with T2DM, cardiovascular disease may well be very dreaded and particularly fearful outcome of diabetes, which may in turn explain the inflated risk estimation. In the case of diabetes mellitus, overestimation of the risk may discourage people to engage in self-care and generate negative emotions and maladaptive behaviors (e.g., compensatory eating) rather than positive health-promoting behaviors. A higher level of pessimism goes along with more psychological distress resulting in decrease in psychological well-being.
Among persons with T2DM, optimism was positively correlated with QOL, and these results correspond well with those of previous studies reported in the literature. The current findings revealed that optimism had a more positive impact on (psychological) health-related QOL among T2DM persons. This can be explained by the fact that optimism enables people to think honestly about themselves and to overcome the worries and stressors that are present in everyday life. Optimistic individuals in the face of stressful events show self-reliance and are more likely to consider positive outcomes about the future and use more problem-oriented coping strategies to deal with the problems. Given the increasing incidence of diabetes and its associated health challenges, a positive state of mind among people diagnosed with T2DM is thus likely to enhance their QOL while undergoing treatment options. Prior studies found similar results showing that positive beliefs have a positive relationship with various dimensions of QOL. For example, Vilhena et al. found that dispositional optimism is more likely to play a significant role in QOL pathways among patients with chronic ailments.
The findings of this study have important implications for the delivery of diabetes prevention and treatment programs. Our findings highlight that T2DM persons had relatively low optimism with a significant decline in the QOL and experiencing higher levels of psychological distress. There is an urgent need for them to explore psychological interventions to encourage patients combating psychological distress by boosting positive psychological states such as optimism. More recently, positive psychology (PP) interventions proved their efficacy in improving psychological well-being. These interventions use exercises (e.g., gratitude letters, acts of kindness, personal strengths) completed in a systematic manner to boost optimism, positive affect, and resilience. These interventions are designed to increase positive psychological well-being across a variety of different populations, including those considered to be psychologically healthy. Further research is necessary to clarify their effectiveness to promote optimism among people with chronic diseases such as T2DM.
A major limitation of the study was a relatively small sample size. The spread of the COVID-19 infection and the safety measure of subsequent lockdown had made an impact on getting an adequate sample. Second, there is an overrepresentation of women in our sample, and our results should not be generalized to both genders as we did not consider the particular environmental factors that could be influenced by biological sex. Finally, samples were taken from clinical settings and could not represent community as a whole; a community-based study is warranted for better representation.
| Conclusions|| |
T2DM persons had shown pessimistic disposition and experiencing psychological distress with a significant decline in the QOL.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Shaw JE, Sicree RA, Zimmet PZ. Global estimates of the prevalence of diabetes for 2010 and 2030. Diabetes Res Clin Pract 2010;87:4-14.
Anderson RJ, Freeland KE, Clouse RE, Lustman PJ. The prevalence of co-morbid depression in adults with diabetes: A meta-analysis. Diabetes Care 2001;24:1069-78.
Ali S, Stone MA, Peters JL, Davies MJ, Khunti K. The prevalence of co-morbid depression in adults with type 2 diabetes: A systematic review and meta-analysis. Diabet Med 2006;23:1165-73.
Sartorius N. Depression and diabetes. Diabetes Clin Neurosci 2018;20:47-52.
Rosa V, Tomai M, Lauriola M, Martino G. Body mass index, personality traits, and body image in Italian pre-adolescents: An opportunity for overweight prevention. Psihologija 2019;52:379-93.
Clarke DM, Currie KC. Depression, anxiety and their relationship with chronic diseases: A review of the epidemiology, risk and treatment evidence. Med J Aust 2009;190:554-60.
Huang CJ, Chiu HC, Lee MH, Wang SY. Prevalence and incidence of anxiety disorders in diabetic patients: A national population-based cohort study. Gen Hosp Psychiatry 2011;33:8-15.
Collins MM, Corcoran P, Perry IJ. Anxiety and depression symptoms in patients with diabetes. Diabet Med 2009;26:153-61.
Lewko J, Zarzycki W, Krajewska-Kułak E. Relationship between the occurrence of symptoms of anxiety and depression, quality of life, and level of acceptance of illness in patients with type 2 diabetes. Saudi Med J 2012;33:887-94.
Rod NH, Grønbaek M, Schnohr P, Prescott E, Kristensen TS. Perceived stress as a risk factor for changes in health behaviour and cardiac risk profile: A longitudinal study. J Intern Med 2009;266:467-75.
Vogelzangs N, Kritchevsky SB, Beekman AT, Newman AB, Satterfield S, Simonsick EM, et al.
Depressive symptoms and change in abdominal obesity in older persons. Arch Gen Psychiatry 2008;65:1386-93.
Wexler DJ, Grant RW, Wittenberg E, Bosch JL, Cagliero E, Delahanty L, et al.
Correlates of health-related quality of life in type 2 diabetes. Diabetologia 2006;49:1489-97.
Jannoo Z, Wah YB, Lazim AM, Hassali MA. Examining diabetes distress, medication adherence, diabetes self-care activities, diabetes-specific quality of life and health-related quality of life among type 2 diabetes mellitus patients. J Clin Transl Endocrinol 2017;9:48-54.
Hermanns N, Kulzer B, Krichbaum M, Kubiak T, Haak T. Affective and anxiety disorders in a German sample of diabetic patients: Prevalence, comorbidity and risk factors. Diabet Med 2005;22:293-300.
Mosaku K, Kolawole B, Mume C, Ikem R. Depression, anxiety and quality of life among diabetic patients: A comparative study. J Natl Med Assoc 2008;100:73-8.
Scheier MF, Carver CS. Effects of optimism on psychological and physical well-being: Theoretical overview and empirical update. Cognit Ther Res 1992;16:201-28.
Nabi H, Koskenvuo M, Singh-Manoux A, Korkeila J, Suominen S, Korkeila K, et al.
Low pessimism protects against stroke: The Health and Social Support (HeSSup) Prospective Cohort Study. Stroke 2010;41:187-90.
Carver CS, Scheier MF. On the structure of behavioural self-regulation. In: Boekaerts M, Pintrich PR, Zeidner M, editors. Handbook of Self-Regulation. The Netherlands: Elsevier; 2000. p. 41-84.
Carver CS, Scheier MF, Segerstrom SC. Optimism. Clin Psychol Rev 2010;30:879-89.
Nes LS, Segerstrom SC, Sephton SE. Engagement and arousal: Optimism's effects during a brief stressor. Pers Soc Psychol Bull 2005;31:111-20.
Giltay EJ, Kamphuis MH, Kalmijn S, Zitman FG, Kromhout D. Dispositional optimism and the risk of cardiovascular death: The Zutphen Elderly Study. Arch Intern Med 2006;166:431-6.
Kostka T, Jachimowicz V. Relationship of quality of life to dispositional optimism, health locus of control and self-efficacy in older subjects living in different environments. Qual Life Res 2010;19:351-61.
Rothrock NE, Hays RD, Spritzer K, Yount SE, Riley W, Cella D. Relative to the general US population, chronic diseases are associated with poorer health-related quality of life as measured by the Patient Reported Outcomes Measurement Information System (PROMIS). J Clin Epidemiol 2010;63:1195-204.
Hackett RA, Steptoe A. Psychosocial factors in diabetes and cardiovascular risk. Curr Cardiol Rep 2016;18:95.
McLeroy KR, Bibeau D, Steckler A, Glanz K. An ecological perspective on health promotion programs. Health Educ Q 1988;15:351-77.
Scheier MF, Carver CS, Bridges MW. Distinguishing optimism from neuroticism (and trait anxiety, self-mastery, and self-esteem): A reevaluation of the Life Orientation Test. J Pers Soc Psychol 1994;67:1063-78.
The World Health Organization Quality of Life Assessment (WHOQOL): Development and general psychometric properties. Soc Sci Med 1998;46:1569-85.
Lovibond SH, Lovibond PF. Manual for the Depression Anxiety Stress Scales. 2nd ed. Sydney:Psychology Foundation, 1995.
Carver CS, Pozo C, Harris SD, Noriega V, Scheier MF, Robinson DS, et al.
How coping mediates the effect of optimism on distress: A study of women with early stage breast cancer. J Pers Soc Psychol 1993;65:375-90.
Burger JM, Palmer ML. Changes in and generalization of unrealistic optimism following experiences with stressful events: Reactions to the 1989 California earthquake. Pers Soc Psychol Bull 1992;18:39-43.
Fournier M, Ridder DD, Bensing J. Is optimism sensitive to the stressors of chronic disease? The impact of type I diabetes mellitus and multiple sclerosis on optimistic beliefs. Psychol Health 2003;18:277-94.
Shnek ZM, Irvine J, Stewart D, Abbey S. Psychological factors and depressive symptoms in ischemic heart disease. Health Psychol 2001;20:141-5.
Kaveh MH, Ghahremani L, Nazari M, Zare S. Quality of life in diabetic patients: The predicting role of personal resources. J Health Sci Surveill Syst 2018;6:142-8.
Gallo LC, Matthews KA. Understanding the association between socioeconomic status and physical health: Do negative emotions play a role? Psychol Bull 2003;129:10-51.
Volpato S, Maraldi C, Fellin R. Type 2 diabetes and risk for functional decline and disability in older persons. Curr Diabetes Rev 2010;6:134-43.
Didarloo A, Alizadeh M. Health-related quality of life and its determinants among women with diabetes mellitus: A cross-sectional analysis. Nurs Midwifery Stud 2016;5:e28937.
Issa B, Baiyewu O. Quality of life of patients with diabetes mellitus in a Nigerian teaching hospital. Hong Kong J Psychiatry 2006;16:27-33.
Chew BH, Mohd-Sidik S, Shariff-Ghazali S. Negative effects of diabetes-related distress on health-related quality of life: An evaluation among the adult patients with type 2 diabetes mellitus in three primary healthcare clinics in Malaysia. Health Qual Life Outcomes 2015;13:187.
Gebremedhin T, Workicho A, Angaw DA. Health-related quality of life and its associated factors among adult patients with type II diabetes attending Mizan Tepi University Teaching Hospital, Southwest Ethiopia. BMJ Open Diabetes Res Care 2019;7:e000577.
Aschalew AY, Yitayal M, Minyihun A. Health-related quality of life and associated factors among patients with diabetes mellitus at the University of Gondar referral hospital. Health Qual Life Outcomes 2020;18:62.
Snoek FJ, Bremmer MA, Hermanns N. Constructs of depression and distress in diabetes: Time for an appraisal. Lancet Diabetes Endocrinol 2015;3:450-60.
Khan P, Qayyum N, Malik F, Khan T, Khan M, Tahir A. Incidence of anxiety and depression among patients with type 2 diabetes and the predicting factors. Cureus 2019;11:e4254.
Larijani B, Bayat MK, Gorganil MK, Bandarian F, Akhondzadeh S, Sadjadi SA. Association between depression and diabetes. Ger J Psychiatry 2004;7:62-5.
Legato MJ, Gelzer A, Goland R, Ebner SA, Rajan S, Villagra V, et al.
Gender-specific care of the patient with diabetes: Review and recommendations. Gend Med 2006;3:131-58.
Pouwer F. Should we screen for emotional distress in type 2 diabetes mellitus? Nat Rev Endocrinol 2009;5:665-71.
Khuwaja AK, Lalani S, Dhanani R, Azam IS, Rafique G, White F. Anxiety and depression among outpatients with type 2 diabetes: A multi-centre study of prevalence and associated factors. Diabetol Metab Syndr 2010;2:72.
Khuwaja AK, Kadir MM. Gender differences and clustering pattern of behavioural risk factors for chronic non-communicable diseases: Community-based study from a developing country. Chronic Illn 2010;6:163-70.
Kumar B, Gautam SK, Khan MS, Giri R, Agarwal S, Anita. Prevalence of depression, anxiety and stress among patients of type 2 diabetes mellitus and effect of glycemic control on depression anxiety and stress in tertiary care center. Int J Med Sci Curr Res 2020;3:226-35.
Mendenhall E, Shivashankar R, Tandon N, Ali MK, Narayan KM, Prabhakaran D. Stress and diabetes in socioeconomic context: A qualitative study of urban Indians. Soc Sci Med 2012;75:2522-9.
Asimakopoulou KG, Skinner TC, Spimpolo J, Marsh S, Fox C. Unrealistic pessimism about risk of coronary heart disease and stroke in patients with type 2 diabetes. Patient Educ Couns 2008;71:95-101.
Covello VT, Peters RG. Women's perceptions of the risks of age-related diseases, including breast cancer: Reports from a 3-year research study. Health Commun 2002;14:377-95.
Scheier MF, Weintraub JK, Carver CS. Coping with stress: Divergent strategies of optimists and pessimists. J Pers Soc Psychol 1986;51:1257-64.
Ramkisson S, Pillay BJ, Sartorius B. Diabetes distress and related factors in South African adults with type 2 diabetes. J Endocrinol Metab Diabetes S Afr 2016;21:35-9.
Simon UO. Health-related optimism and quality of life among diabetes patients: The moderating role of clinical factors in Nigerian sample. Open Access J Addict Psychol 2018; 1: 1-6.
Vilhena E, Pais-Ribeiro J, Silva I, Pedro L, Meneses RF, Cardoso H, et al.
Psychosocial factors as predictors of quality of life in chronic Portuguese patients. Health Qual Life Outcomes 2014;12:3.
Fredrickson BL. The role of positive emotions in positive psychology. The broaden-and-build theory of positive emotions. Am Psychol 2001;56:218-26.
[Table 1], [Table 2], [Table 3], [Table 4]