Prevalence of and Factors Associated with Diabetic Retinopathy in Patients with Diabetes Mellitus at Siriraj Hospital – Thailand’s Largest National Tertiary Referral Center

Figures & data

Table 1 Prevalence, Type, and Severity of DR Among Diabetic Patients Attending the DM Clinic of Siriraj Hospital

Diabetic Retinopathy	N (%)
No DR	737 (65.22)
DR	393 (34.78)
NPDR	301 (26.64)
Mild NPDR	143
Moderate NPDR	147
Severe NPDR	11
PDR	92 (8.14)

Abbreviations: DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy.

Figure 1 Prevalence of diabetic retinopathy stratified according to age group (A) and duration of diabetes (B).

Figure 2 Prevalence of diabetic retinopathy in different types of diabetes stratified according to duration of diabetes (A) and severity of diabetic retinopathy (B).

Table 2 Demographic and Clinical Characteristics of Diabetic Patients Compared Between Those with and without DR

Parameters	No DR (N = 737)	DR (N = 393)	p-value
Age (years)	58.91 ± 17.64	63.51 ± 13.12	<0.001
Male	276 (37.4)	145 (36.9)	0.890
Female	461 (62.6)	248 (63.1)
Duration of DM (years)	11.76 ± 7.82	16.85 ± 8.69	<0.001
Type of diabetes
Type 1 diabetes (N = 67)	55 (7.5)	12 (3.1)	0.025
Type 2 diabetes (N = 1028)	653 (88.6)	375 (95.4)	0.002
Other types of diabetes (N = 35)	29 (3.9)	6 (1.5)	0.052
Smoker^a	69 (12.7)	33 (11.7)	0.803
Total daily dose of insulin (units)	48.05 ± 26.68	51.75 ± 29.83	0.214
Number of oral antidiabetic drugs	1.65 ± 1.11	1.69 ± 1.13	0.524
Systolic BP (mmHg)	133.29 ± 17.26	135.86 ± 18.34	0.023
Diastolic BP (mmHg)	76.06 ± 10.86	74.42 ± 11.00	0.017
BMI (kg/m^2)	25.96 ± 5.45	26.10 ± 4.94	0.666
Waist circumference (cm)	91.98 ± 12.20	93.47 ± 13.20	0.364
Hip circumference (cm)	98.78 ± 9.40	100.25 ± 11.8	0.306
Fasting plasma glucose (mg/dL)	148.65 ± 48.93	154.30 ± 63.41	0.127
HbA1c (%)	7.51 ± 1.47	8.04 ± 1.59	0.001
Total cholesterol (mg/dL)	164.53 ± 32.11	161.98 ± 35.14	0.251
Triglyceride (mg/dL)	135.54 ± 82.81	131.15 ± 71.06	0.365
LDL-cholesterol (mg/dL)	84.95 ± 27.42	83.78 ± 29.22	0.529
HDL-cholesterol (mg/dL)	53.30 ± 15.65	51.98 ± 15.93	0.207
Serum creatinine (mg/dL)	1.04 ± 0.75	1.47 ± 1.36	<0.001
eGFR (mL/min/1.73 m^2)	77.52 ± 30.33	61.18 ± 30.95	<0.001
Albuminuria (mg/g Cr)^b
<30	367 (61.1)	135 (45.2)	<0.001
30–300	145 (24.1)	96 (32.1)	<0.001
>300	89 (14.8)	68 (22.7)	<0.001

Notes: Data were reported in mean ± standard deviation or number (percentage), as appropriate. ^aData of smoking status, N = 825, No DR (N = 542), DR (N = 283). ^bData of albuminuria, N = 900, No DR (N = 601), DR (N = 299).

Abbreviations: DR, diabetic retinopathy; DM, diabetes mellitus; BP, blood pressure; BMI, body mass index; HbA_1c, glycated hemoglobin; LDL-cholesterol, low-density lipoprotein cholesterol; HDL-cholesterol, high-density lipoprotein cholesterol; eGFR, estimated glomerular filtration rate.

Table 3 Demographic and Clinical Characteristics of Diabetic Patients Compared Between Those with No DR and Those with NPDR, and Between Those with No DR and Those with PDR

Parameters	No DR (N = 737)	NPDR (N = 301)	p-value*	PDR (N = 92)	p-value**
Age (years)	59.03 ± 17.46	65.08 ± 12.01	<0.001	58.20 ± 13.2	0.641
Male	276 (37.4)	119 (39.5)	0.330	26 (28.3)	0.072
Female	461 (62.6)	182 (60.5)		66 (71.7)
Duration of DM (years)	11.87 ± 7.87	16.49 ± 8.33	<0.001	18.21 ± 8.88	<0.001
Type of diabetes
Type 1 diabetes	55 (7.5)	6 (2.0)	0.023	6 (6.5)	0.818
Type 2 diabetes	653 (88.6)	290 (96.3)	0.001	85 (92.4)	1.000
Other types of diabetes	29 (3.9)	5 (1.7)	0.024	1 (1.1)	0.762
Smoker^a	70 (12.9)	24 (11.2)	0.353	9 (13.2)	0.025
Total daily dose of insulin (units)	48.05 ± 26.68	50.84 ± 27.06	0.364	54.2 ± 37.28	0.302
Number of oral antidiabetic drugs	1.65 ± 1.11	1.81 ± 1.12	0.038	1.35 ± 1.15	0.025
Systolic BP (mmHg)	133.29 ± 17.26	135.52 ± 19.20	0.083	137.94 ± 15.25	0.010
Diastolic BP (mmHg)	76.06 ± 10.86	75.00 ± 10.74	0.153	72.61 ± 11.94	0.012
BMI (kg/m^2)	25.96 ± 5.45	25.84 ± 4.78	0.762	27.24 ± 5.48	0.063
Waist circumference (cm)	91.98 ± 12.20	92.49 ± 12.77	0.765	98.31 ± 14.62	0.111
Hip circumference (cm)	98.78 ± 9.40	99.51 ± 11.92	0.640	103.69 ± 10.92	0.100
Fasting plasma glucose (mg/dL)	148.65 ± 48.93	164.20 ± 48.98	<0.001	142.81 ± 53.86	0.344
HbA1c (%)	7.51 ± 1.47	7.90 ± 1.50	0.002	7.89 ± 1.34	0.018
Total cholesterol (mg/dL)	164.53 ± 32.11	162.76 ± 33.42	0.617	166.42 ± 31.06	0.616
Triglyceride (mg/dL)	135.54 ± 82.81	131.42 ± 74.84	0.510	133.44 ± 57.56	0.772
LDL-cholesterol (mg/dL)	84.95 ± 27.42	83.71 ± 28.68	0.643	87.75 ± 27.00	0.385
HDL-cholesterol (mg/dL)	53.30 ± 15.65	52.10 ± 15.75	0.312	52.20 ± 16.39	0.585
Serum creatinine (mg/dL)	1.04 ± 0.75	1.33 ± 1.03	< 0.001	1.89 ± 1.96	<0.001
eGFR (mL/min/1.73 m^2)	77.52 ± 30.33	62.83 ± 29.78	< 0.001	55.91 ± 33.84	<0.001
Albuminuria (mg/g Cr)^b
<30	367 (61.1)	103 (46.0)	< 0.001	32 (42.7)	<0.001
30–300	145 (24.1)	69 (30.8)	0.001	27 (36.0)	<0.001
>300	89 (14.8)	52 (23.2)	0.001	16 (21.3)	<0.001

Notes: Data were reported in mean ± standard deviation or number (percentage), as appropriate. ^aData of smoking status, N = 825, No DR (N = 542), NPDR (N = 215), PDR (N = 68). ^bData of albuminuria, N = 900, No DR (N = 601), NPDR (N = 224), PDR (N = 75). *p-value when No DR was compared with NPDR. **p-value when No DR was compared with PDR.

Abbreviations: DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; DM, diabetes mellitus; BP, blood pressure; BMI, body mass index; HbA_1c, glycated hemoglobin; LDL-cholesterol, low-density lipoprotein cholesterol; HDL-cholesterol, high-density lipoprotein cholesterol; eGFR, estimated glomerular filtration rate.

Table 4 Metabolic and Blood Pressure Control Compared Between Those with No DR and Those with DR, Between Those with No DR and Those with NPDR, and Between Those with No DR and Those with PDR

Parameters	No DR (N = 737)	DR (N = 393)	p-value*	NPDR (N = 301)	p-value**	PDR (N = 92)	p-value***
SBP >140 mmHg	226 (30.7%)	160 (40.7%)	0.001	122 (40.5%)	0.002	38 (41.3%)	0.039
DBP >90 mmHg	72 (9.8%)	32 (8.1%)	0.389	26 (8.6%)	0.729	6 (6.5%)	0.452
FPG ≥130 mg/dL	442 (60.0%)	231 (58.8%)	0.703	182 (60.5%)	0.732	49 (53.3%)	0.223
HbA1c >7%	393 (53.3%)	278 (70.7%)	<0.001	215 (71.4%)	<0.001	63 (68.5%)	0.076
TC ≥200 mg/dL	88 (11.9%)	45 (11.5%)	0.847	36 (12.0%)	0.917	9 (9.8%)	0.616
TG ≥150 mg/dL	230 (31.2%)	112 (28.5%)	0.377	85 (28.2%)	0.381	27 (29.3%)	0.906
LDL-C ≥100 mg/dL	238 (32.3%)	120 (30.5%)	0.591	87 (28.9%)	0.247	33 (35.9%)	0.413
HDL-C <40 mg/dL	180 (24.4%)	119 (30.3%)	0.050	90 (29.9%)	0.170	29 (31.5%)	0.267

Notes: Data were reported in number (percentage). * p-value when No DR was compared with DR. ** p-value when No DR was compared with NPDR. *** p-value when No DR was compared with PDR.

Abbreviations: DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; HbA_1c, glycated hemoglobin; TC, total cholesterol; TG, triglyceride; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol.

Table 5 Univariate Analysis for Factors Significantly Associated with DR in Patients with Diabetes

Risk Factors	Adjusted Odds Ratio (95% CI)	p-value
Type of diabetes
Type 1 diabetes	1.00
Type 2 diabetes	1.97 (1.10, 3.54)	0.025
Other types	0.68 (0.24, 1.95)	0.612
Duration of diabetes (years)
<5	1.00
5–9.9	2.33 (1.44, 3.76)	<0.001
10–14.9	3.36 (2.10, 5.39)	<0.001
15–19.9	3.68 (2.26, 5.99)	<0.001
≥20	7.48 (4.66, 12.01)	<0.001
Albuminuria (mg/g Cr)
<30	1.00
≥30 and <300	2.94 (2.10, 4.13)	<0.001
≥300	4.62 (3.20, 6.68)	<0.001
Neuropathy	4.37 (3.09, 6.19)	<0.001
Previous foot ulcer	5.85 (3.52, 9.73)	<0.001
Foot amputation	4.73 (2.05, 10.95)	<0.001
History of angina pectoris	1.52 (1.03, 2.23)	0.033
Coronary artery disease	1.69 (1.12, 2.54)	0.011
Heart failure	3.37 (1.84, 6.19)	<0.001
Cerebrovascular disease	2.51 (1.63, 3.86)	<0.001
Peripheral vascular disease	3.48 (1.64, 7.40)	0.001
Hypertension	2.13 (1.55, 2.93)	<0.001
Foot deformity	2.10 (1.20, 3.68)	0.009
Dorsalis pedis and posterior tibial artery pulse
Decrease	2.55 (1.47,4.40)	0.001
Absence	5.40 (1.89,15.43)	0.001
Loss of protective sensation (monofilament test)	3.74 (2.67, 6.16)	<0.001

Abbreviation: CI, confidence interval.

Table 6 Multivariate Analysis for Factors Independently Associated with DR in Patients with Diabetes

Risk Factors	Beta-Coefficient	Standard Error	p-value
Model 1
Duration of diabetes	0.084	0.020	<0.001
Albuminuria (mg/g Cr)
<30	0.428	0.167	<0.001
≥30 and <300	0.757	0.384	0.048
≥300	0.072	0.393	0.885
HbA1c	0.225	0.093	0.006
eGFR	0.008	0.006	0.136
Loss of protective sensation (monofilament test)	0.976	0.323	0.003
Model 2
Duration of diabetes	0.091	0.020	<0.001
Albuminuria (mg/g Cr)
<30	0.294	0.152	<0.001
≥30 and <300	0.935	0.365	0.010
≥300	0.160	0.388	0.681
HbA1c	0.244	0.090	0.012
Loss of protective sensation (monofilament test)	1.089	0.314	0.001

Abbreviations: HbA_1c, glycated hemoglobin; eGFR, estimated glomerular filtration rate.

Table 7 Medications Used Among Diabetic Patients Compared Between Those with and without DR

Medication	No DR (N = 737)	DR (N = 393)	p-value
Insulin	271 (36.8%)	247 (62.8%)	<0.001
Insulin use only	94 (12.8%)	70 (17.8%)	0.016
Insulin plus oral antidiabetic drugs	177 (24.0%)	177 (45.0%)	<0.001
Oral antidiabetic drugs
1 drug	193 (26.2%)	86 (21.9%)	0.112
2 drugs	249 (33.8%)	134 (34.1%)	1.000
3 drugs	135 (18.3%)	77 (19.6%)	0.522
>3 drugs	31 (4.2%)	19 (4.8%)	0.650
Antihypertensive drugs	530 (71.9%)	332 (84.5%)	<0.001
Lipid-lowering agents	618 (83.9%)	331 (84.2%)	0.865

Note: Data were reported in number (percentage).

Abbreviation: DR, diabetic retinopathy.