Red blood cell distribution width and the risk of being in poor glycemic control among patients with established type 2 diabetes

Figures & data

Figure 1 Selection of the study population.

Abbreviations: FPG, fasting plasma glucose; PG, postprandial glucose; HbA1c, hemoglobin A1c.

Table 1 Distribution of risk factors in relation to glycemic control status

	Well-controlled group	Poorly-controlled group	P-value
	n=145	n=557
Age (years)	60.9±8.4	62.1±9.5	0.161
Gender male (%)	60 (41.4)	254 (45.6)	0.362
DM duration (years)	7.9±1.4	7.8±1.7	0.176
BMI (kg m^−2)	25.6±3.4	26.7±3.2	<0.001
WHR	0.91 (0.73–1.07)	0.93 (0.75–1.24)	<0.001
FPG (mmol L^−1)	6.0±0.6	10.6±2.9	<0.001
2-h PG (mmol L^−1)	7.8±1.4	17.5±4.1	<0.001
HbA1c (%)	6.16±0.35	7.86±0.52	<0.001
Current smoker, n (%)	17 (12.3)	105 (19.34)	0.12
Current drinker, n (%)	11 (9.1)	71 (15.1)	0.016
Hypertension, n (%)	80 (55.6)	298 (53.6)	0.674
Hyperlipidemia, n (%)	60 (41.7)	182 (32.7)	0.045
Family history of diabetes, n (%)	63 (43.5)	267 (47.9)	0.516
TC (mmol L^−1)	5.03±1.04	5.33±1.27	0.009
TG (mmol L^−1)	1.41±0.75	1.87±1.55	<0.001
HDL-C (mmol L^−1)	1.41±0.36	1.31±0.33	0.001
LDL-C (mmol L^−1)	3.06±0.85	3.25±0.94	0.031
WBC count (10^12 L^−1)	6.16±1.71	6.61±1.49	0.002
RBC count (10^12 L^−1)	4.21±0.54	4.31±0.49	0.039
Leukocyte count (10^12 L^−1)	1.95±0.67	2.10±0.66	0.017
Neutrophil count (10^12 L^−1)	3.74±1.35	4.01±1.15	0.018
Hemoglobin (g L^−1)	129.1±16.7	130.3±16.2	0.061
MCV (fl)	93.3±5.6	92.5±4.4	0.071
RDW (%)	14.12±0.67	13.95±0.52	<0.001

Notes: Continuous data are shown as mean ± standard deviation or median (interquartile range) and categorical data are shown as frequency (%). P-values ≤0.05 are shown in bold.

Abbreviations: DM, diabetes mellitus; BMI, body mass index; WHR, waist–hip ratio; FPG, fasting plasma glucose; PG, postprandial glucose; HbA1c, hemoglobin A1c; TC, total cholesterol; TG, triglyceride; HDL-C, high-density lipoprotein; LDL-C, low-density lipoprotein; WBC, white blood cell; RBC, red blood cell; MCV, mean corpuscular volume; RDW, red cell distribution width.

Table 2 Distribution of risk factors in relation to RDW

	Q1	Q2	Q3	Q4	P-value
	n=130	n=181	n=191	n=200
RDW range	<13.6	13.6–13.8	13.9–14.3	>14.3
Age (years)	59.8±9.6	60.6±8.9	62.8±9.0	63.3±9.3	0.001
Gender male (%)	70 (53.8)	82 (45.3)	88 (46.1)	74 (37)	0.025
BMI (kg m^−2)	26.3±3.3	26.5±3.2	26.6±3.1	26.4±3.4	0.856
WHR	0.92 (0.89–0.95)	0.92 (0.88–0.96)	0.92 (0.89–0.96)	0.92 (0.88–0.97)	0.692
FPG (mmol L^−1)	8.8±4.4	8.9±4.3	8.5±3.9	8.4±3.9	0.001
2-h PG (mmol L^−1)	10.6±3.7	9.7±3.2	9.5±2.9	9.2±3.1	<0.001
HbA1c (%)	8.32±1.53	8.05±1.38	8.02±1.53	7.89±1.48	0.087
Current smoker, n (%)	30 (23.6)	29 (16.7)	42 (22.8)	21 (10.7)	0.035
Current drinker, n (%)	17 (16.5)	21 (13.4)	23 (14.7)	21 (12.2)	0.829
Hypertension, n (%)	58 (44.9)	91 (50.1)	114 (60.0)	115 (57.5)	0.029
Hyperlipidemia, n (%)	30 (23.3)	60 (33.2)	79 (41.6)	73 (36.5)	0.008
Family history of diabetes, n (%)	78 (60)	91 (50.3)	80 (41.9)	81 (40.5)	0.002
TC (mmol L^−1)	5.03±1.37	5.22±1.32	5.29±1.13	5.26±1.16	0.944
TG (mmol L^−1)	1.91±1.72	1.88±1.70	1.70±1.31	1.66±1.03	0.269
HDL-C (mmol L^−1)	1.31±0.35	1.31±0.34	1.33±0.30	1.39±0.36	0.088
LDL-C (mmol L^−1)	3.20±0.95	3.17±0.93	3.27±0.89	3.20±0.93	0.756
WBC count (10^12 L^−1)	6.66±1.49	6.34±1.52	6.46±1.45	6.64±1.70	0.169
RBC count (10^12 L^−1)	4.29±0.50	4.30±0.50	4.29±0.43	4.27±0.56	0.952
Leukocyte count (10^12 L^−1)	2.01±0.63	2.07±0.64	2.08±0.68	2.10±0.69	0.713
Neutrophil count (10^12 L^−1)	4.15±1.11	3.82±1.19	3.87±1.07	4.02±1.35	0.064
Hemoglobin (g L^−1)	133.9±17.4	133.8±16.8	131.6±14.7	128.2±18.1	0.003
MCV (fl)	93.5±3.6	93.4±3.8	92.8±3.9	91.6±6.3	<0.001

Notes: Continuous data are shown as mean ± standard deviation or median (interquartile range) and categorical data are shown as frequency (%). P-values ≤0.05 are shown in bold.

Abbreviations: RDW, red cell distribution width; Q, quartile; BMI, body mass index; WHR, waist–hip ratio; FPG, fasting plasma glucose; PG, postprandial glucose; HbA1c, hemoglobin A1c; TC, total cholesterol; TG, triglyceride; HDL-C, high-density lipoprotein; LDL-C, low-density lipoprotein; WBC, white blood cell; RBC, red blood cell; MCV, mean corpuscular volume.

Table 3 Binary logistic regression models evaluating the association of RDW with the risk of being in poor glycemic control

	Q1	Q2	P-value	Q3	P-value	Q4	P-value
		OR (95% CI)		OR (95% CI)		OR (95% CI)
Unadjusted	1.00 (reference)	0.6 (0.4–1.2)	0.153	0.8 (0.4–1.5)	0.526	0.5 (0.3–0.8)	0.007
Model 1	1.00 (reference)	0.6 (0.3–1.2)	0.146	0.8 (0.4–1.5)	0.407	0.4 (0.2–0.8)	0.005
Model 2	1.00 (reference)	0.6 (0.3–1.3)	0.227	0.7 (0.3–1.5)	0.323	0.3 (0.2–0.7)	<0.001
Model 3	1.00 (reference)	0.7 (0.3–1.4)	0.283	0.7 (0.3–1.5)	0.354	0.3 (0.2–0.6)	0.002

Notes: Model 1 adjusted for age and gender. Model 2 adjusted for age, gender, BMI, WHR, family history of diabetes, smoking status, drinking status, hypertension and hyperlipidemia. Model 3 adjusted for age, gender, BMI, WHR, family history of diabetes, smoking status, drinking status, hypertension, hyperlipidemia and WBC count. P-values ≤0.05 are shown in bold.

Abbreviations: RDW, red cell distribution width; Q, quartile; OR, odds ratio; CI, confidence interval; BMI, body mass index; WHR, waist–hip ratio; WBC, white blood cell.

Table 4 Odds ratio with 95% confidence intervals for glycemic control in quartiles of RDW according to tertiles of BMI, TC, HDL-C and LDL-C

Interactive factors	Qs of RDW	Events (n)	OR (95% CI)	P-value	P for interaction
BMI					0.014
Tertile 1	Q1	36	1.00 (reference)
Tertile 1	Q2	48	0.51 (0.16–1.63)	0.255
Tertile 1	Q3	49	0.98 (0.28–3.44)	0.980
Tertile 1	Q4	60	0.20 (0.07–0.59)	0.004
Tertile 2	Q1	33	3.16 (0.45–22.02)	0.246
Tertile 2	Q2	60	1.26 (0.27–5.87)	0.768
Tertile 2	Q3	51	0.55 (0.12–2.54)	0.44
Tertile 2	Q4	46	1.05 (0.21–5.23)	0.951
Tertile 3	Q1	34	1.07 (0.21–5.23)	0.935
Tertile 3	Q2	45	1.60 (0.30–8.53)	0.581
Tertile 3	Q3	50	3.07 (0.52–17.98)	0.214
Tertile 3	Q4	62	1.07 (0.22–5.17)	0.934
TC					0.028
Tertile 1	Q1	30	1.00 (reference)
Tertile 1	Q2	48	0.87 (0.21–3.54)	0.842
Tertile 1	Q3	45	2.23 (0.43–11.40)	0.337
Tertile 1	Q4	61	0.21 (0.04–1.22)	0.083
Tertile 2	Q1	38	0.20 (0.05–0.71)	0.013
Tertile 2	Q2	62	0.15 (0.03–0.77)	0.023
Tertile 2	Q3	51	0.16 (0.03–0.85)	0.031
Tertile 2	Q4	50	0.10 (0.02–0.52)	0.006
Tertile 3	Q1	35	0.96 (0.11–8.36)	0.971
Tertile 3	Q2	44	0.33 (0.05–2.04)	0.233
Tertile 3	Q3	54	0.21 (0.04–1.25)	0.087
Tertile 3	Q4	57	0.31 (0.05–1.82)	0.192
HDL-C					0.809
Tertile 1	Q1	37	1.00 (reference)
Tertile 1	Q2	53	0.84 (0.19–3.72)	0.814
Tertile 1	Q3	42	0.56 (0.12–2.58)	0.456
Tertile 1	Q4	50	0.46 (0.11–1.96)	0.295
Tertile 2	Q1	30	0.63 (0.10–4.08)	0.628
Tertile 2	Q2	49	0.74 (0.12–4.72)	0.751
Tertile 2	Q3	63	0.96 (0.15–6.04)	0.964
Tertile 2	Q4	47	0.42 (0.07–2.55)	0.346
Tertile 3	Q1	36	0.96 (0.15–6.00)	0.968
Tertile 3	Q2	52	0.36 (0.07–1.91)	0.232
Tertile 3	Q3	45	0.52 (0.09–2.98)	0.467
Tertile 3	Q4	71	0.24 (0.05–1.26)	0.091
LDL-C					0.003
Tertile 1	Q1	31	1.00 (reference)
Tertile 1	Q2	52	1.03 (0.25–4.31)	0.968
Tertile 1	Q3	43	1.72 (0.36–8.16)	0.496
Tertile 1	Q4	59	0.15 (0.04–0.56)	0.005
Tertile 2	Q1	38	0.28 (0.05–1.68)	0.164
Tertile 2	Q2	54	0.12 (0.02–0.62)	0.011
Tertile 2	Q3	53	0.17 (0.03–0.96)	0.045
Tertile 2	Q4	53	0.14 (0.03–0.74)	0.021
Tertile 3	Q1	34	0.53 (0.08–3.64)	0.052
Tertile 3	Q2	48	0.36 (0.06–2.13)	0.258
Tertile 3	Q3	54	0.25 (0.04–1.5)	0.130
Tertile 3	Q4	56	0.39 (0.07–2.29)	0.295

Notes: Data are adjusted for age, gender, family history of diabetes, smoking status, drinking status, hypertension and hyperlipidemia. P-values ≤0.05 are shown in bold.

Abbreviations: RDW, red cell distribution width; Q, quartile; BMI, body mass index; TC, total cholesterol; HDL-C, high-density lipoprotein; LDL-C, low-density lipoprotein; OR, odds ratio; CI, confidence interval.