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ORIGINAL RESEARCH

Sight-threatening Diabetic Retinopathy and

Associated Risk Factors Among Adult Diabetes
Patients at Debre Tabor General Hospital,
Northwest Ethiopia
This article was published in the following Dove Press journal:
Clinical Ophthalmology

Getasew Alemu Mersha 1 Background: People with diabetes have an increased risk of developing sight-threatening
Asamere Tsegaw Woredekal2 conditions. Sight threatening diabetic retinopathy (STDR) is an advanced microvascular of
Matyas Tilahun Tesfaw3 complication of diabetes on the eye. It remains one of the leading causes of preventable
1
blindness among working age adults around the world. There is a paucity of evidence on the
Department of Optometry, School of
Medicine, University of Gondar prevalence of STDR and its associated factors in Ethiopia, particularly in the study area.
Comprehensive Specialized Hospital, Therefore, the aim of our study was to determine the prevalence of STDR and its associated
Gondar, Ethiopia; 2Department of factors among adult diabetes patients at Debre Tabor General Hospital (DTGH), Northwest
Ophthalmology, School of Medicine,
University of Gondar Comprehensive Ethiopia.
Specialized Hospital, Gondar, Ethiopia; Materials and Methods: An institution-based cross-sectional study was conducted on 306
3
Department of Ophthalmology, School
diabetes patients at Debre Tabor General Hospital with systematic random sampling techni­
of Medicine, Debre Tabor University,
Debre Tabor, Ethiopia que. Semi-structured questionnaire, document review and physical examination were applied
to collect the data. Binary and multivariable logistic regression model were used to identify
associated factors for STDR.
Results: The majority of the participants 163 (53.3%) were type 1 diabetes (T1DM) and the
mean age of T1 and T2 DM participants was 34.5 (12.8) and 58.7 (10.7) years respectively.
The prevalence of STDR was 15.3% (95%CI: 9.6%–20.9%) and 11.9% (6.6–17.5) in T1DM
and T2DM, respectively. Low family monthly income (adjusted odds ratio (AOR)=4.4, 95%
CI: 1.05–18.40) among T2DM, longer duration of diabetes (AOR=10.9, 95%CI: 2.94–40.4)
among T1DM (AOR=3.54, 95CI: 1.06–11.8) among T2DM and poor glycemic control
(AOR=3.93, 95%CI: 1.06–14.5) and hypertension (AOR=5.86, 95%CI: 1.20–28.6) among
T1DM and BMI (AOR=4.79, 95%CI: 1.35–17.00) among T2DM were significantly asso­
ciated with STDR.
Conclusion and Recommendation: The prevalence of STDR was high. Low family
monthly income, longer duration of diabetes, poor glycemic control, hypertension and
obesity were positively associated with STDR. Early screening of STDR and improving
diabetes self management in all diabetes patients were recommended.
Keywords: STDR, prevalence, Ethiopia

Correspondence: Getasew Alemu Mersha

Department of Optometry, School of Introduction
Medicine, University of Gondar Diabetic retinopathy (DR) is a common and specific microvascular complication of
Comprehensive Specialized Hospital,
Gondar 196, Ethiopia diabetes, characterized by spectrum of lesions in the retina. Clinically, diabetic
Tel +251932823935 retinopathy can be graded as non-sight-threatening diabetic retinopathy (NSTDR)
Fax +251-58-114 1240
Email gechopta12@gmail.com including mild and moderate nonproliferative abnormalities and sight-threatening

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diabetic retinopathy (STDR) which includes severe non­ August 28, 2020. The hospital is located in Debre Tabor
proliferative abnormalities, proliferative abnormalities and town, the capital city of South Gondar zone of the Amhara
diabetic maculopathy.1,2 National Regional State, and it is located 667 km from
In the initial stage of the disease, people do not have visual Addis Ababa. According to the Debre Tabor Hospital
impairment and may not notice any visual symptoms. Planning and Information Department, the hospital is pro­
However, in its advance form of complication (STDR), the viding preventive and curative health care services for about
disease progress into proliferative phase which is character­ ~2.7 million people in the zone and nearby districts and has
ized by formation of new blood vessels and macular edema a capacity of 250 beds for inpatient services in five disci­
owing to accumulation of fluid within the retina producing plines and 12 outpatient departments (OPDs).13 The hospi­
severe and often irreversible vision loss. In addition, the new tal has specialty chronic illness clinics where patients with
blood vessels may bleed, adding further complication of pre­ specific chronic diseases are referred for follow-up. On
retinal or vitreous hemorrhage. Finally, neovascular glaucoma average around 22 DM patients are visiting the two diabetic
associated with the new vessels can be a cause of visual loss.1 clinics per day during working hours and general practi­
Globally, the prevalence of DR and STDR among diabetic tioners, internists and nurses are involved in the clinical
adults was estimated to be 34.6% and 10.2% respectively.3 The service of diabetes patients. Secondary eye care service is
prevalence of DR in Africa was reported to be 31.6%4 while given in the hospital with three optometrists, two ophthal­
the national prevalence of DR in Ethiopia was 19.48%.5 Out of mic nurses, one cataract surgeon and one ophthalmologist.
139 million visual impaired worldwide 3.7 (1.9%) million
were visually impaired due to STDR.6 Visual impairment as Inclusion Criteria
a result of STDR has a significant impact on patients’ quality of All adult diabetes patients of age ≥18 years visiting the
life, and can compromise their ability to manage their disease diabetic clinic in DTGH during the study period were
successfully, which can in turn have a positive impact on the included and diabetes patients who were previously diag­
incidence of other diabetic complications and negative impact nosed for DR or not were also included in the study.
on overall life expectancy and productivity.7
The major risk factors for the development STDR in Exclusion Criteria
diabetes patients are longer duration of diabetes, hyperglyce­ Patient with pregnancy induced diabetes (gestational dia­
mia, inflammation, dyslipidemia, obesity, puberty, pregnancy betes), patients who were severely ill unable to sit and be
and hypertension.8–10 Complete understanding of the magni­ examined with slit lamp indirect ophthalmoscope and
tude of STDR in the patient population is crucial to design patients with media opacity that obscured the view of
policies for prevention and timely treatment of the disease. their retina were excluded from the study.
Preservation of sight in STDR can be achieved through The sample size was determined based on a single popu­
effective screening, timely laser treatment, intraocular lation proportion formula by taking 7.3% of the prevalence
injection of steroids and antivascular endothelial growth- of STDR from a similar study done in Jimma, Ethiopia,14
factor agents and intraocular surgery.11,12 95%CI, 3% margin of error and 10% nonresponse rate.
Despite the magnitude of DR is widely known through Accordingly, the final computed sample size was 319.
the previous studies, limited data is available on the mag­ A systematic random sampling technique was applied to
nitude and underlying risk factors of STDR in Ethiopia, select study participants: there are around 750 diabetes
besides no study has been conducted in the study area so patients who visit the diabetic clinic over two months.
far. The purpose of this study is, therefore, to determine Based on the decision to collect data in two months
the prevalence of STDR and associated factors among a sampling interval “k” was determined by dividing the
adult diabetes patients attending Debre Tabor General expected number of DM patients with the sample size 319
Hospital (DTGH), Northwest Ethiopia. which was approximately two. Then every other diabetes
patient was approached for the study. Ethical clearance
was obtained from University of Gondar, College of
Methods and Materials Medicine and Health Sciences, School of Medicine ethical
Study Design and Period review committee. Moreover, permission to conduct the
A hospital-based cross-sectional study was conducted at study in the hospital was obtained from Chief Executive
Debre Tabor General Hospital from June 29, 2020 to Officer and Medical Director Offices of DTGH. Written

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Dovepress Alemu Mersha et al

informed consent was obtained from each participant level was >152 mg/dL, or 7% glycated hemoglobin
before they were recruited in the study. The written according to American Diabetic Association Standards of
informed consent was approved by the ethical review Medical Care in Diabetes.17
committee. Generally, the study was conducted in line Physical activity was defined as
with the Ethical Principle of the Declaration of Helsinki.
● Physical inactivity: anyone who does not to perform

Data Collection Procedures and Quality any form of physical activity for at least 10 min per day.
● Low physical activity: anyone who performs moderate
Control activities (walking, running, or cycling) less than five
Semi-structured interviewer-administered questionnaire,
days for at least 30 min or vigorous intensity activities
document review and ocular examination were used to col­
(like carrying or lifting heavy loads or digging) less
lect data. The questionnaire consisted of four sections:
than three days for at least 20 min per week.
Sociodemographic and economic variables (six items),
● Moderate physical activity: anyone who performs mod­
Behavioral measurements (14 items), diabetic follow-up
erate activity for more than five days for at least 30 min
and eye checkup (five items) and checklist for clinical data
per day or vigorous intensity activity more than three
extraction (seven items). Data quality was ensured through
days for at least 20 min per day.18
pretesting the questioner on 5% of the sample before the
actual data collection period and training of the data collec­
Alcohol consumption was defined based on National
tors. Each day during the data collection 5% of the data was
Institute on Alcohol Abuse and Alcoholism:19
cross checked for completeness by the principal investigator.
Three BSc nurses interviewed the participants and
● Nondrinkers (ie, abstainers, or no alcohol consump­
traced data on type of DM, hypertension, FBS, and mode
tion history),
of treatment from the patients’ medical folder they also
● Moderate drinkers (ie, up to one drink/day for women
measured height and weight of participants. Retinal exam­
and up to two drinks/day for men), and
ination was carried out with a 90 diopter of Volk lens with
● Heavy drinkers (ie, >1 drink/day for women and >2
slit lamp biomicroscope by a trained senior optometrist
drinks/day for men).
after the pupillary dilation was done using 1% tropicamide
eye drop on both eyes. Participants with complexity and/or
issue of sight-threatening retinopathy were double seen by Data Processing and Analysis
a senior ophthalmologist and an agreed diagnosis of STDR The data were entered into Epi Info 7 and exported to
was taken. An eye with the highest grade of diabetic SPSS version 20 for analysis. The descriptive statistics
retinopathy was labeled as having STDR. was summarized and presented using summary statistics
Labeling of NSTDR and STDR was done based on the such as frequency tables. The model was checked by
Proposed International Clinical Diabetic Retinopathy and Hosmer–Lemeshow goodness of fit test. Binary logistic
Diabetic Macular Edema Disease Severity Scales.15,16 regression was used to identify candidate variables.
Previously undiagnosed diabetic retinopathy was used to Variables with p-value <0.2 in binary logistic regression
refer retinopathy that was not diagnosed through dilated were entered into a multivariable logistic regression
retinal examination before. model. Variables having p-values <0.05 were considered
as statistically significant.
Assessment and Definition of Risk
Factors Results
Known diabetes and hypertension were assigned for the Sociodemographic Characteristics
participants who had confirmed diagnosis of diabetes or A total of 306 (type 1 DM=163 and type 2 DM=143)
hypertension previously. Newly diagnosed diabetes was participants completed the study with a response rate of
assigned for the patients with zero years of diabetes dura­ 95.9%. The mean age of type 1 and type 2 DM partici­
tion. Type of DM was assigned to participants as it was pants was 34.5 (12.8) and 58.7 (10.7) years respectively.
confirmed and written in their medical folder. Glycemic From both types of DM, the majority of the participants
control was defined as poor if a current fasting blood sugar were male (57.1%, 51.0%), being currently married

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Alemu Mersha et al Dovepress

(58.3%, 75.5%) and had no formal education (56.4%, T1DM and 104 (72.7%) of T2DM participants had pre­
55.2) (Table 1). The median family monthly income of vious dilated retinal examination. Only 47 (28.80) of
the type 1 and type 2 DM participants was 3700 (3252.9) T1DM participants and 33 (23.1) of T2DM had awareness
and 3180 (3493.8) Ethiopian Birr (ETB) respectively. about diabetic retinopathy (Table 2).

Clinical and Behavioral Characteristics of Prevalence of DR and STDR Among

Study Participants Participants
The median duration of T1 and T2DM participants was 5 Among the total study participants, the overall prevalence of
(6.4) and 4 (5.9) years respectively. The median level of DR of any severity was found to be 96 (31.4%) among them
FBS was 140 (105.6) and 159 (65) mg/dL for T1DM and 34 (27%) did not have prior dilated retinal examination. The
T2DM participants respectively. In both types of DM,
majority of the participants had a moderate level of phy­
Table 2 Clinical and Behavioral Characteristics of Study
sical activity (65.0%, 45.5%), visited the diabetes clinic
Participants at Debre Tabor General Hospital Northwest
every month (73.0%, 76.2%) and not obese (95.7%, Ethiopia, 2020 (n=306)
86.7%). Regarding prior retinal evaluation, 76 (46.6%) of
Variable Type 1 n (%) Type 2 n (%)

Duration of DM (in years)

Table 1 Sociodemographic and Economic Characteristics of
<10 116 (76.4) 89 (62.2)
Study Participants at Debre Tabor General Hospital, Northwest
≥10 47 (43.6) 54 (37.8)
Ethiopia, 2020 (n=306)
Variable Type 1 n (%) Type 2 n (%) Glycemic control
Good control 93 (57.1) 62 (43.4)
Gender Poor control 70 (42.9) 81 (56.6)
Male 93 (57.1) 73 (51.0)
Female 70 (42.9) 70 (49.0) Mode of treatment
Insulin alone 160 (98.2) 20 (14.0)
Age (years) Tablet 1 (0.6) 116 (81.1)
<46 133 (83.6) 21 (14.7) Combined 2 (1.2) 7 (4.9)
≥46 30 (18.4) 122 (85.3)
Drinking status
Marital status Nondrinker 89 (54.6) 104 (72.7)
Currently single 68 (41.7) 35 (24.5) Moderate drinker 60 (36.8) 31 (21.7)
Currently married 95 (58.3) 108 (75.5) Heavy drinker 14 (8.6) 8 (5.6)

Educational status Physical activity

No formal education 92 (56.4) 79 (55.2) Physical inactivity 18 (11.0) 36 (25.2)
Formal Education 71 (43.6) 64 (44.8) Low physical activity 39 (23.9) 42 (29.4)
Moderate physical activity 106 (65.0) 65 (45.5)
Occupational status
Government employee 22 (13.5) 33 (23.1) Hypertension
Retired 1 (0.6) 22 (15.4) Yes 19 (11.7) 76 (53.1)
House wife 12 (7.4) 31 (21.7) No 144 (88.3) 67 (46.9)
Farmer 64 (39.3) 26 (18.2)
Other 29 (17.8) 18 (12.6) Body mass index (BMI)
No job 35 (21.5) 13 (9.1) Not obese 156 (95.7) 124 (86.7)
Obese 7 (4.3) 19 (13.3)
Residence
Urban 81 (49.7) 112 (78.3) Family history of DM
Rural 82 (50.3) 31 (21.7) Yes 39 (23.9) 33 (23.1)
No 124 (76.1) 110 (76.9)
Family monthly income
(ETB)a History of dilated retinal
<3700 81 (49.7) 72 (50.3) exam
≥3700 82 (50.3) 71 (49.7) Yes 76 (46.6) 104 (72.7)
No 87 (53.4) 39 (27.3)
Notes: n=sample size. aIncome and age were categorized based on their median
values. Note: n=sample size.

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prevalence of STDR was 13.7% (95%CI: 9.8–17.6%) among nearly 11 times (AOR=10.90, 95%CI: 2.94–40.4) and
them 13 (10.3%) did not have prior dilated among T2DM were 3.5 times (AOR=3.54, 95%CI: 1.06–­
fundus examination (Table 3) and only 3 (3.1%) had prior 11.8) more likely to develop STDR compared to those who
laser treatment for DR. Based on the type of DM, the pre­ had a duration of less than 10 years (Tables 5 and 6). T1DM
valence of DR was 51 (31.3%) and 45 (31.5%) in T1DM and participants who had a poor glycemic control had nearly
T2DM respectively. The prevalence of STDR was 15.3% four times (AOR=3.93, 95%CI: 1.06–14.5) an increased
(95%CI: 9.6–20.9%) among T1DM and it was 11.9% (95% risk of having STDR compared to those who had a good
CI: 6.6–17.5%) among T2DM (Table 4). glycemic control (Table 5). T1DM Participants who had
a comorbid hypertension were nearly six times (AOR=5.86,
Factors Associated with Sight-threatening 95%CI: 1.20–28.6) more at risk to develop STDR (Table 5).
Diabetic Retinopathy Regarding BMI, T2DM participants who were obese were
On applying bivariable logistic regression analysis among nearly five times (AOR=4.79, 95%CI; 1.35–17.0) more
T1DM participants: age, family history of diabetes, family likely to develop STDR compared with participants who
monthly income, duration of diabetes, glycemic control, were not obese (Table 6).
and comorbid hypertension were statistically and signifi­
cantly associated with STDR. Among T2DM participants: Discussion
family monthly income, duration of DM and BMI were In this study the higher proportion of diabetics were T1DM
statistically and significantly associated with STDR. 163 (53.3%), owing to the current pandemic some of T2DM
However, in multivariable logistic regression analysis patients were not coming to the clinic during the study
among T1DM duration of diabetes, glycemic control and period, taking medication through their attendants. The over­
comorbid hypertension were remained statistically and all prevalence of STDR among all adult diabetes patients
significantly associated with STDR. Among T2DM family attending at Debre Tabor General Hospital, Northwest,
monthly income, duration of DM and BMI were statisti­ Ethiopia was found to be 13.70%. Our finding was in line
cally and significantly associated with STDR. with the findings of studies conducted in mainland China
Reference to family monthly income of the T2DM par­ (12.6%),20 Zimbabwe (11.40%),21 and Uganda (14.6).22
ticipants, those who had an income of <3180 ETB were 4.4 However, our finding was higher than findings reported
times (AOR=4.40, 95%CI: 1.05–18.4) more likely to have from population-based studies in Singapore (8.90%)23 and
STDR compared to those who had an income of ≥3180 ETB Zambia (5.5%).24 This variation could be accountable for
(Table 6). Regarding the duration of DM, participants who the difference in study population characteristics and label­
had a duration of 10 years and above among T1DM were ing of STDR. For instance, labeling of STDR in the
Zambian study excluded diabetic maculopathy, however,
our study included diabetic maculopathy in labeling of
Table 3 Prevalence of DR and STDR Among Adult Diabetes at
Debre Tabor General Hospital, Northwest Ethiopia, August 2020 STDR. Similarly our finding was higher than that reported
(n = 306) from previous hospital based studies in Alaska, USA
(4.2%)25 and Jimma, Ethiopia (7.3%).14 The difference
Stages of DR Prevalence n (%) 95%CI
in the labeling of STDR was the possible cause of these
DR of any severity 96 (31.4) 26.1–36.3
variations.
STDRa 42 (13.7) 9.8–17.6
Alternatively, our finding was lower than population-
Previously undiagnosed STDR 13 (10.3) 5.6–15.7
a
based studies done in Tanzania (23%),26 besides the study
Notes: Included severe NPDR, PDR, and DME.
setting the difference in the mean duration of diabetes
contributed for this discrepancy. Similarly, our finding
Table 4 Prevalence of DR and STDR Among Adult Type 1 and was also lower than Hangzhou, China (80%),27 Fiji
Type 2 Diabetes at Debre Tabor General Hospital, Northwest
(27%),28 and Malawi (29.4%).29 The discrepancy could
Ethiopia, August 2020 (n = 306)
be attributed to the difference in study settings and dura­
Stages of DR Type 1 n (%) 95%CI Type 2 n (%) 95%CI tion of diabetes. The study in China was at a retina clinic
DR of any severity 51 (31.3) 24.0–38.0 45 (31.5) 23.9–39.4 where patients with retinopathy were linked for a better
STDRa 25 (15.3) 9.6–20.9 17 (11.9) 6.6–17.5 treatment and follow-up, while the Malawi study was in
Notes: aIncluded severe NPDR, PDR, and DME. a tertiary center where patients with advanced conditions

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Table 5 Bivariable and Multivariable Logistic Regression Analysis of Factors Associated with STDR Among Type I DM
at Debre Tabor General Hospital, Northwest Ethiopia, August 2020 (n=306)
Variable Sight-threatening Diabetic COR (95%CI) AOR (95%CI)
Retinopathy (STDR) n (%)

Yes No

Age
<46 6 82 1.00 1.00
≥46 19 56 3.93 (1.74–12.34)* 0.79 (0.18–3.46)

Gender
Male 19 74 1.00 1.00
Female 6 64 0.37(0.14–0.97)* 0.29 (0.18–3.46)

Marital status
Currently single 6 62 1.00 1.00
Currently married 19 76 2.58 (0.97–6.86) 4.56 (1.05–19.82)

Family monthly income (ETB)

<3700 18 63 3.06 (1.20–7.80)* 2.93 (0.84–10.2)
≥3700 7 75 1.00 1.00

Duration of DM
<10 years 5 111 1.00 1.00
≥10 years 20 27 16.44(5.66–47.8)** 10.9 (2.94–40.4)**

Glycemic control
Good control 6 87 1.00 1.00
Poor control 19 51 5.40 (2.03–14.40)* 3.93 (1.06–14.5)*

Hypertension
Yes 9 10 7.20 (2.54–20.37)** 5.86 (1.20–28.6)*
No 16 128 1.00 1.00

Family history of DM
Yes 12 27 3.80 (1.56–9.24)* 1.09 (0.29–4.11)
No 13 111 1.00 1.00

History of dilated eye check up

Yes 15 61 1.00 1.00
No 10 77 0.53 (0.22–1.26) 1.35(0.39–4.65)

Awareness on DR
Yes 11 36 1.00 1.00
No 14 102 0.45 (0.19–1.08) 0.51 (0.14–1.98)
Notes: n=sample size. *p-value <0.05 **p-value <0.001. Hosmer–Lemeshow test=0.112.
Abbreviation: ETB, Ethiopian Birr.

were actually referred for a better evaluation and treatment The prevalence of STDR among T2DM participants
and therefore, probing STDR in these settings could result was 11.9% which was similar to Nepal (8.3%),33 India
in high prevalence. (9.5%),34 and Saudi Arabia (16.3%).35 Nevertheless, this
With reference, the types of DM, the prevalence of STDR report was lower than Pakistan (17.6%)36 and higher
among T1DM participants was 15.3%, this was higher than than California, USA (0.5%),37 Pittsburgh, USA
reported from Slovakia (5.76%)30 and Gondar, Ethiopia (19.0%),38 and Slovakia (3.35).30 These discrepancies
(6.3%)31 however, it was lower than Norway (26.0%).32 The might be attributable to the difference in mean duration
difference in mean duration of DM and labeling of STDR in of diabetes, the nature of study population and definition
these studies contributed to the variation of figures. of STDR.

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Table 6 Bivariable and Multivariable Logistic Regression Analysis of Factors Associated with STDR Among Type 2 DM at Debre Tabor
General Hospital, Northwest Ethiopia, August 2020 (n=306)
Variable Sight-threatening Diabetic Retinopathy (STDR) n (%) COR (95%CI) AOR (95%CI)

Yes No

Family monthly income (ETB)

<3180 14 58 5.47 (1.50–19.98)* 4.40 (1.05–18.4)*
≥3180 3 68 1.00 1.00

Duration of DM
<10 years 7 107 1.00 1.00
≥10 years 10 19 8.05 (2.73–23.74)** 3.54 (1.06–11.8)*

Glycemic control
Good control 4 58 1.00 1.00
Poor control 13 68 2.77 (0.86–8.97) 3.14 (0.83–11.9)

BMI
Not obese (<30) 9 115 1.00 1.00
Obese (≥30) 8 11 9.29 (2.99–28.93)** 4.79 (1.35–17.0)*
Notes: n=Sample Size. *p-value <0.05 **p-value <0.001. Hosmer–Lemeshow test=0.151.
Abbreviation: ETB, Ethiopian Birr.

Our study also found out that, family monthly income, developing STDR compared to those who had a good
duration of diabetes, glycemic control, hypertension and glycemic control. In this regard, our finding was similar
BMI were important risk factors of STDR. The likelihood to the findings previously reported in Norway,32 mainland
of having STDR was high among T2DM participants who China,20 and India.34 A poorly controlled high glucose
had an average monthly income of <3180 ETB. This level instigates a cascade of events leading to retinal
finding was in accordance with the finding of studies in vascular endothelial dysfunction eventually leading to
India39 and Sudan.40 The possible reason for the associa­ advanced diabetic retinopathy.11
tion could be, participants with low monthly income may Our study identified that T1DM participants with
have constraints to cover their transportation, investigation comorbid hypertension were more likely to develop
and medication related costs all the time and these factors STDR compared to those without comorbid hypertension,
are interrelated and may lead to poor glycemic control and this finding was in accordance with studies in California,
in turn linked to advanced diabetic complications, includ­ USA,37 mainland China,20 and Malawi,29 that comorbid
ing STDR. hypertension was positively associated with advanced dia­
Our finding demonstrated that, the likelihood of devel­ betic retinopathy. Hypertension exacerbates diabetic reti­
oping STDR was high for both types of DM participants nopathy through increased blood flow and mechanical
with longer duration of diabetes (≥10 years) and this was damage (stretching) of vascular endothelial cells, stimulat­
consistent with what has been found previously in ing release of vascular endothelial growth factor which
Norway,32 Hangzhou, China,27 mainland China,20 further increase the severity of the disease.11
India,34 Cameroon,41 and Malawi29 that longer duration Moreover, our study showed that obese T2DM partici­
diabetes was associated with the development of vision- pants had an increased risk of developing STDR compared
threatening diabetic retinopathy. This might be due the fact to those who were not obese. This result agreed with the
that in diabetes there are abnormalities in energy produc­ finding of a Croatian42 study which reported that the
tion which are thought to be the major contributor to the progression of diabetic retinopathy among T2DM signifi­
development of advanced diabetic complications like cantly increased with higher BMI. Obesity could be asso­
STDR, and these abnormalities are considered to occur ciated with local inflammation of the retina and increase
late in the development of the disease.2 oxidative stress to the endothelial cells in turn elevate
Our study also indicated that T1DM participants who vascular endothelial factor which is responsible for the
had a poor glycemic control had an increased risk of progression of DR to STDR.

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The limitation of our study includes: single center and 9. Ting DSW, Cheung GCM, Wong TY. Diabetic retinopathy: global
prevalence, major risk factors, screening practices and public health
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may not be representative of the overall population with 10. Yau JW, Rogers SL, Kawasaki R, et al. Global prevalence and major
diabetes, and this affects the generalizability of our find­ risk factors of diabetic retinopathy. Diabetes Care. 2012;35
(3):556–564. doi:10.2337/dc11-1909
ing. Finally, we used current fasting glucose level instead 11. Cheung N, Mitchell P, Wong TY. diabetes care. Lancet. 2010;21:22.
of glycated hemoglobin for glycemic status; the latter 12. Njeri LN. Prevalence of Diabetic Retinopathy and Barriers to Uptake
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The authors report no conflict of interest in this work. factors associated with retinopathy in diabetic patients at
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