Prevalence and burden of diabetes mellitus-related symptoms in patients with type 2 diabetes mellitus: A cross-sectional study

Abstract Introduction: Type 2 diabetes mellitus (T2DM) is a significant non-communicable disease in Malaysia, with a prevalence of 18.1%, per the National Health and Morbidity Survey. This study aimed to determine the prevalence and burden of diabetes mellitus-related symptoms and whether these symptoms were addressed by primary care doctors. Methods: This 1-month cross-sectional study was conducted at an urban hospital-based primary care clinic in Malaysia. Patients with T2DM were recruited using systematic random sampling. Participants answered a self-administered questionnaire adapted from the Diabetes Symptom Checklist-Revised, which evaluated the sociodemographic characteristics, burden of diabetes mellitus-related symptoms in the past month and post-consultation feedback about symptoms. Data were analysed using SPSS. Results: Four hundred eighteen participants were included, yielding a response rate of 97.7%. Hyperglycaemia was the most prevalent symptom, with 48.1% of the participants reporting a frequent need to empty their bladder. Most participants experienced a low symptom burden, so 56.7% did not report their symptoms to their doctors. The participants who reported their symptoms had a higher symptom burden. Among them, 97.5% indicated that their doctors addressed their symptoms. Approximately 78% reported satisfaction and good coping skills when their symptoms were addressed. Conclusion: Hyperglycaemia was the most prevalent diabetes mellitus-related symptom among the patients with T2DM. The symptom burden was generally low, so most patients did not report their symptoms to their doctors. Those who reported their symptoms had a higher symptom burden. Further studies must explore why patients do not report their symptoms and how doctors address patients’ symptoms.


Introduction
Diabetes mellitus substantially impacts the quality of life (QoL) of patients by a ecting their physical, mental and social wellbeing. 1Patients with type 2 diabetes mellitus (T2DM) may experience physical symptoms such as acute or chronic pain, fatigue or neuropathy and psychological symptoms such as depression, sleep disturbances or emotional disability. 2 T2DM-related symptoms can be as burdensome as the disease itself.e prevalence of these symptoms ranges from 3% to 48%. 2 Patients with T2DM have been reported to have a poorer QoL than their healthy counterparts. 3spite their impact on QoL, diabetes mellitusrelated symptoms are often not reported by patients.Most studies are focused on hypoglycaemia among patients with T2DM most likely because it is the most burdensome symptom. 3In contrast, limited studies have investigated the burden of other diabetes mellitus-related symptoms among patients with T2DM.
In Malaysia, the prevalence of T2DM is high. 1 Accordingly, it is important to study the burden of diabetes mellitus-related symptoms and whether these symptoms are addressed by doctors, especially among patients with a high symptom burden, to consequently improve their QoL.
Patients with T2DM have a poorer healthrelated QoL (HRQoL) than their healthy counterparts.Sociodemographic characteristics, disease control and symptoms are determinants of the HRQoL of patients with T2DM. 4 A substantial number of patients report a poorer HRQoL owing to pain/discomfort, mobility problems, anxiety/depression, reduced activity performance and impaired ability for selfcare. 5Some patients with T2DM also develop complications such as ischaemic heart disease, stroke and neuropathy, further worsening their HRQoL. 6Older patients with T2DM tend to have a higher symptom burden than their younger counterparts.One study showed that patient-reported symptoms in older patients were risk factors for hospitalisation and emergency department visits. 7study conducted by the American Diabetes Association found that 56% of patients with T2DM experienced at least one diabetes mellitus-related symptom in the past 12 months.8 Patients with T2DM may also have emotional and psychological needs that must be addressed.9 Accordingly, the symptom burden is a patient concern.10 Addressing diabetes mellitus-related symptoms may improve patients' emotional and psychological wellbeing.
It is also essential to know whether doctors address patients' symptoms because such symptoms are as important as their concerns.Two-thirds of patients have been shown to worry that their symptoms might represent a serious illness.Accordingly, identifying and addressing patients' concerns are a crucial part of the patient-centred approach. 11rrent clinical practice focuses on the control of HbA1c levels and prevention of complications of T2DM rather than control of symptoms.Patients with T2DM may have symptoms, which may burden them. is study sought to conduct a proper clinical assessment and provide symptom relief to patients.Symptoms can be an indicator of disease progress or a complication of the disease, such as atherosclerosis. 12Diabetes mellitusspeci c symptoms are important predictors that facilitate a patient-centred approach.is study then aimed to identify the prevalence and burden of diabetes mellitus-related symptoms among patients with T2DM and the degree of symptom management by primary care doctors.

Design
A prospective cross-sectional study was conducted from 1 October 2019 to 30 November 2019 at the Department of Primary Care Medicine in University Malaya Medical Centre, a tertiary hospital located in Kuala Lumpur, Malaysia.

Participants
Patients with T2DM who were aged ≥18 years and able to understand either English or Malay language were included in the study.ose who were cognitively impaired were excluded from the study.

Instrument
A self-administered questionnaire adapted from the Diabetes Symptom Checklist-Revised (DSC-R), with an additional section assessing participant demographics, was used.Its English version was translated to Malay language by two independent translators who were pro cient in both languages.e Malay version was reviewed by an expert panel. is version underwent backward translation to English by two other independent translators who were also pro cient in both languages.
e questionnaire had two sections: preconsultation and post-consultation.e preconsultation section assessed the participants' sociodemographic and clinical characteristics and diabetes mellitus-related symptoms.e modi ed DSC-R consisted of 34 diabetes mellitus-related symptoms, requiring the participants to respond either 'yes' or 'no' if they had any of those symptoms in the past 4 weeks.ose who responded 'yes' for each symptom were required to rate their symptom burden on a Likert scale ranging from 1 ('not at all troublesome') to 5 ('extremely troublesome').For the post-consultation section, the participants indicated their feedback regarding their consultation.

Pilot study
A pilot study was conducted among 30 participants prior to the actual data collection to identify any issues with the questionnaire and the recruitment process.ese participants were able to understand the questionnaire and, on average, took about 20 min to complete it.No changes were made to the questionnaire after the pilot study.
Subsequently, patients with T2DM were recruited via systematic random sampling.Eligible participants received the preconsultation questionnaire before their consultation and the post-consultation questionnaire after their consultation with their doctors.

Main study
A total of 1602 patients with T2DM were identi ed at the triage counter of the hospital within 1 month.ese patients were randomly and systematically recruited, with one selected for every three.A total of 534 patients were selected.Among them, 54 were unable to read or understand English or Malay; 11 refused to participate; and nine had a cognitive impairment.Consequently, 460 patients remained and agreed to participate; they were given the Patient information sheet to read, and the consent form to sign.Once the consent form was signed, the participants were asked to complete the questionnaire.A total of 418 participants completed and returned the questionnaires.
e primary outcome of this study was the prevalence of symptoms during the past 4 weeks.e secondary outcome was the symptom burden, which was assessed using a Likert scale.Other outcomes included symptoms reported to doctors and whether doctors addressed such symptoms.418 respondents returned questionaire Each questionaire checked for completeness If any missing date, the respondent was kindly requested to ll in the question All 418 respondents' records were assesed through the EMR system Data analysis Data were analysed using SPSS version 23.0 by IBM, Chicago, United States of America.Descriptive statistics were used to describe the sociodemographic and clinical data of the participants.Categorical variables were presented as percentages and frequencies and continuous variables as means with standard deviations (SDs).
e independent variables were the sociodemographic and clinical characteristics, while the dependent variables were the symptom score, subscale score and post-consultation feedback.e association of the sociodemographic and clinical characteristics with the prevalence of symptoms and the symptom score was also evaluated.

Ethical considerations
Ethical approval was obtained from the University Malaya Medical Ethics Committee before commencement of the study (MREC  ref. no.: 201973-7602).Written informed consent was obtained from all participants.

Results
A total of 471 patients were eligible for inclusion, of whom 11 refused to participate, and 42 who consented did not return the questionnaires.
is yielded a response rate of 88.7%.e participants had a mean age of 63 years.Approximately 55.5% were women, and 41.8% were Malays.Most participants (80.6%) had T2DM for more than 5 years, with a mean HbA1c level of 7.98% (Table 1).Prevalence and burden of diabetes mellitus-related symptoms e prevalence of diabetes mellitus-related symptoms ranged from 4.1% to 48.1%.e most commonly reported symptoms were frequent need to empty the bladder (48.1%), numbness of the hands (43.5%), lack of energy (42.6%) and numbness of the feet (40.9%).

Management of symptoms by doctors
Approximately 83.5% of the participants had previously consulted their attending doctors.Among them, 38% discussed their symptoms with their doctors.Approximately 88.1% (n=140) reported one to three symptoms, with a mean number of symptoms of 2.26 (SD=1.6)(Table 5).Nearly all participants (97.5%) indicated that their symptoms were addressed by their doctors; most were satis ed (89.3%) with how their symptoms were addressed and were con dent (78.0%) in coping with their symptoms.

Discussion
is study showed that the overall prevalence of diabetes mellitus-related symptoms and the prevalence of each symptom among the patients with T2DM were quite low and below 50%, respectively.e participants in this study were generally old with a long disease duration, but the prevalence of symptoms was lower than expected.e most commonly reported symptoms were related to hyperglycaemia, possibly re ecting disease control.Most symptoms were acknowledged and addressed satisfactorily by the doctors of the participants.e prevalence of symptoms ranged from 4.1% to 48%, while the symptom burden score ranged from 1.76 to 2.58, re ecting a low symptom burden.
ese ndings di er from the report by García et al., wherein the prevalence ranged from 14.1% to 67.6%. 13 authors found that a stronger perception of disease severity was associated with a higher symptom burden.13 In the present study, the low prevalence of symptoms among the participants could be attributed to the relatively average HbA1c level of 7.9%.Müller et al. showed that most patients with T2DM with symptoms had an HbA1c level above 8.9%.14 Similar to the present ndings, the hyperglycaemic symptoms that were most prevalent were frequent urination and tiredness.14 Further, higher HbA1c levels were associated with a higher symptom burden.
Other complications of T2DM may also a ect patients' symptoms.Patients with cardiovascular or ophthalmological complications may have a higher symptom burden.Symptoms of hypoglycaemia may be more prevalent in patients on insulin; however, in this study, the score for this subscale was not signi cant.e patients with a longer T2DM duration tended to have a higher symptom.(Table 5) Among the participants who discussed their symptoms with their doctors, 88.1% reported a total of one to three symptoms.Most of them (97.5%)indicated that their doctors addressed their symptoms.Notably, this study was conducted at a primary care clinic in a tertiary hospital in Malaysia, where patients' expectations tend to be higher.Providing adequate time during consultations contributes to patient satisfaction. 15

Strengths and limitations
e strength of this study is that the ndings are applicable to clinical practice.Patients with an advanced age and a higher HbA1c level may have a higher symptom burden.
ere are several limitations noted in this study.is study was conducted in a single setting, limiting the generalisation of the ndings to other settings in Malaysia.Further, the questionnaire was translated only to Malay.Many patients who were unable to read or understand English or Malay were then excluded from this study.Some patients with visual impairment or stroke would require assistance in completing the questionnaire.Another limitation is that the questionnaire was tested for its face and content validities only; it was not validated with other questionnaires such as the Diabetes Distress Scale and SF-36.Moreover, the symptoms were evaluated retrospectively for the past 4 weeks, so there was a possibility of recall bias.e post-consultation section mainly evaluated the symptoms based on consultation with the doctors.However, the symptoms may not be the primary concern of some patients.e data were also susceptible to recall bias.
Another limitation of this study is that the symptoms reported by the patients with T2DM may be attributed to diseases other than T2DM such as benign prostate hyperplasia (BPH) or overactive bladder syndrome (OAB).Liu et al. reported a high prevalence of OAB among patients with T2DM. 16In other studies, T2DM was found to be associated with BPH in men and bladder dysfunction in women.Berger et al. concluded that diabetic vascular damage may cause hypoxia, which may be involved in the pathogenesis of BPH. 17,18 association of T2DM with prostate or bladder disorder could explain the high prevalence of urinary symptoms among patients with T2DM.

Conclusion
e prevalence and burden of diabetes mellitusrelated symptoms among patients with T2DM are low.Optimisation of glycaemic control is important in reducing the symptom burden.A lower symptom burden results in fewer discussions of symptoms with doctors.Generally, patients with T2DM are satis ed with the management of their symptoms by their doctors.

Figure 1 .
Figure 1.Flowchart of the study and data collection process.

Table 1 .
Sociodemographic and clinical variables of the respondents (N=418).

Table 2 .
Prevalence and burden of diabetes mellitus-related symptoms.

Table 4 .
Association of the mean subscale score with age, HbA1c level and DM duration.

?
• e ndings can bene t individuals practising in the eld of family medicine, especially in areas where non-communicable diseases are prevalent.• e study can assist future researchers in conducting literature reviews.• e study can help future researchers in generating ideas for research in the eld of noncommunicable diseases.• e ndings emphasise the importance of reporting symptoms to doctors.• e ndings can be used as a guide by healthcare practitioners in addressing patients' symptoms.