The Platelet-to-Lymphocyte Ratio Predicts Diabetic Retinopathy in Type 2 Diabetes Mellitus

Figures & data

Table 1 Patients’ Baseline and Clinical Characteristics

Variable	DM (n =142)	DR (n =148)	P
Age (years)	55.23 ± 10.19	57.39 ± 9.34	0.061
Male sex (%)	77 (54.2)	66 (44.6)	0.101
Duration of DM (months)	24 (2–75)	120 (48–156)	< 0.001
BMI (kg/m^2)	24.10 ± 3.25	24.05 ± 3.36	0.977
Smoking (%)	54 (38.0)	47 (31.8)	0.262
Hypertension (%)	46 (32.4)	57 (38.5)	0.276
DPN (%)	27 (19.0)	112 (75.7)	< 0.001
SBP (mmHg)	125 (118–134)	129 (124–143)	0.003
DBP (mmHg)	80 (74–84)	80 (74–87)	0.474
HbA1c (%)	9.10 (7.18–10.70)	9.20 (7.93–11.40)	0.130
TBIL (mmol/L)	9.70 (7.28–14.60)	8.50 (6.00–11.80)	0.001
Scr (umol/L)	56.40 (48.05–68.03)	60.50 (47.63–75.28)	0.062
BUN (mg/dL)	5.73 (4.59–6.78)	6.61 (5.43–8.00)	< 0.001
TG (mmol/L)	2.21 (1.29–3.24)	1.80 (1.21–2.84)	0.188
TC (mmol/L)	4.89 (4.20–5.46)	5.04 (4.22–5.76)	0.215
HDL-C (mmol/L)	1.11 (0.93–1.39)	1.19 (1.01–1.44)	0.026
LDL-C (mmol/L)	2.61 (2.06–3.11)	2.74(2.14–3.37)	0.101
WBCs (10^9/L)	5.88 (5.08–6.85)	6.05 (4.88–6.92)	0.935
Neutrophils (10^9/L)	3.81 (3.31–4.58)	4.23 (3.41–5.01)	0.121
Lymphocytes (10^9/L)	1.57 (1.12–1.88)	1.37 (1.05–1.84)	0.111
Monocytes (10^9/L)	0.30 (0.24–0.37)	0.31 (0.24–0.39)	0.556
Platelets (10^9/L)	158.00 (127.00–193.00)	185.00 (136.00–229.00)	0.001
HGB (g/dL)	141.00 (131.00–151.00)	132.00 (120.00–143.00)	< 0.001
NLR	2.43 (1.98–3.39)	2.91 (2.15–4.04)	0.012
PLR	105.34 (92.41–128.98)	133.10 (102.17–160.59)	<0.001
MLR	0.20 (0.15–0.27)	0.21 (0.17–0.29)	0.043

Notes: Data are expressed as mean ± SD, median (inter-quartile), or percentage. Bold values signify the p<0.05.

Abbreviations: n, number of patients; DM, diabetes mellitus; DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; BMI, body mass index; DPN, diabetic peripheral neuropathy; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, hemoglobin A1c; TBIL, total bilirubin; Scr, serum creatinine; BUN, blood urea nitrogen; TG, triglycerides; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; HGB, hemoglobin; WBC, white blood cell; Hgb, hemoglobin; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio; MLR, monocyte-to-lymphocyte ratio.

Table 2 Comparison of Clinical Characteristics and Hematological Parameters in Patients with and without Retinopathy and Its Severity

Variable	DM (n = 142)	NPDR (n = 124)	PDR (n =24)	P
Age (years)	55.23 ± 10.19	57.69 ± 9.56	55.83 ± 8.18	0.120
Male sex (%)	77(54.2)	57(46.0)	9(37.5)	0.195
Duration of DM (months)	24(2–75)*^#	120(36–144)*^†	138(96–240)^#†	< 0.001
BMI (kg/m^2)	24.10 ± 3.25	24.03 ± 3.19	24.19 ± 4.23	0.968
Smoking (%)	54 (38.0)	41 (33.1)	6 (25.0)	0.400
Hypertension (%)	46 (32.4)	47 (37.9)	10 (41.7)	0.520
DPN (%)	27 (19.0)*^#	89 (71.8)*^†	23 (95.8)^#†	< 0.001
SBP (mmHg)	125 (118–134)*^#	128 (122–143)*	137 (124–153)^#	0.003
DBP (mmHg)	80 (74–84)	80 (74–86)	82 (76–88)	0.652
HbA1c (%)	9.10 (7.18–10.70)^#	9.10 (7.60–11.38)^†	10.30 (9.00–11.88)^#†	0.033
TBIL (mmol/L)	9.70 (7.28–14.60)*^#	8.50 (6.23–11.70)*	7.30 (4.73–12.10)^#	0.006
Scr (umol/L)	56.40 (48.05–68.03)	60.50 (47.63–74.20)	60.45 (48.03–81.88)	0.075
BUN (mg/dL)	5.73 (4.59–6.78)*^#	6.50 (5.43–7.94)*	6.73 (5.33–8.71)^#	< 0.001
TG (mmol/L)	2.21 (1.29–3.24)	1.81 (1.21–2.85)	1.64 (1.21–2.72)	0.794
TC (mmol/L)	4.89 (4.20–5.46)	5.07 (4.23–5.79)	5.01 (4.17–5.55)	0.441
HDL-C (mmol/L)	1.11 (0.93–1.39)	1.18 (1.00–1.44)	1.24 (1.10–150)	0.203
LDL-C (mmol/L)	2.61 (2.06–3.11)	2.77 (2.13–3.46)	2.52 (2.21–2.97)	0.214
WBCs (10^9/L)	5.88 (5.08–6.85)	6.05 (4.89–6.86)	6.07 (4.83–7.33)	0.823
Neutrophils (10^9/L)	3.81 (3.31–4.58)	4.05 (3.33–4.92)	3.95 (3.35–5.01)	0.103
Lymphocytes (10^9/L)	1.57 (1.12–1.88)	1.41 (1.07–1.84)	1.31 (1.05–1.92)	0.728
Monocytes (10^9/L)	0.30 (0.24–0.37)	0.31 (0.24–0.41)	0.31 (0.25–0.31)	0.348
Platelets (10^9/L)	158.00 (127.00–193.00)*	189.50(139.00–234.00)*^†	150.00(117.50–199.50)^†	< 0.001
HGB (g/dL)	141.00(131.00–151.00)*^#	132.00 (120.00–144.50)*^†	125.00(114.50–137.00)^#†	< 0.001
NLR	2.43 (1.98–3.39)*	2.84 (2.08–4.17)*	2.96 (2.35–3.37)	0.025
PLR	105.34 (92.41–128.98)*	137.02 (105.80–165.80)*	107.80 (76.73–141.20)	< 0.001
MLR	0.20 (0.15–0.27)	0.21 (0.17–0.30)	0.22 (0.18–0.27)	0.115

Notes: Data are expressed as mean ± SD, median (inter-quartile), or percentage. *Significant difference between DM and NPDR. ^#Significant difference between DM and PDR; ^†Significant difference between PDR and NPDR; Bold values signify the p<0.05.

Abbreviations: n, number of patients; DM, diabetes mellitus; DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; BMI, body mass index; DPN, diabetic peripheral neuropathy; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, hemoglobin A1c; TBIL, total bilirubin; Scr, serum creatinine; BUN, blood urea nitrogen; TG, triglycerides; TC, total cholesterol; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; HGB, hemoglobin; WBC, white blood cell; Hgb, hemoglobin; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio; MLR, monocyte-to-lymphocyte ratio.

Table 3 Multivariate Analysis of DR in Patients with T2DM

Characteristics	OR	95% CI	P
Duration of DM (months)	1.006	1.001–1.011	0.017
SBP (mmHg)	1.030	1.008–1.052	0.007
DPN (%)	9.305	4.833–17.913	< 0.001
HGB (g/dL)	0.978	0.959–0.997	0.024
PLR	1.020	1.010–1.029	0.026

Note: Bold values signify the p<0.05.

Abbreviations: DR, diabetic retinopathy; T2DM, type 2 diabetes mellitus; SBP, systolic blood pressure; PLR, platelet-to-lymphocyte ratio; HGB, hemoglobin; DPN, diabetic peripheral neuropathy; 95% CI, 95% Confidence interval; OR, Odds Ratio.

Figure 1 The receiver operating characteristic (ROC) curves for the optimal cut-off values of the platelet-to-lymphocyte (PLR) ratio, duration of diabetes mellitus (DM), systolic blood pressure (SBP) and HGB (hemoglobin) as predictors of diabetic retinopathy.