Evaluation of Red Blood Cell Indices for Prediction of Glycemic Control in People Living with Type 2 Diabetes

Figures & data

Figure 1 Sex distribution of patients with type 2 DM in Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023.

Figure 2 Age distribution of patients with type 2 DM in Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023.

Table 1 Clinical and Anthropometric Characteristics of Patients with Type 2 DM in Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023

Variable	Hemoglobin A1C(%)			Chi Squared P-value
	<7	≥7	Total (%)
BMI (kg/m²)
<18.5 (underweight)	0	4	4 (2.0)	0.726
18.5–24.9 (normal weight)	9	79	88 (43.1)
25.0–29.9 (pre-obesity)	5	67	72 (35.3)
≥30 (obesity)	3	37	40 (19.6)
Hypertension history
Yes	11	85	96 (46.4)	0.092
No	6	105	111 (53.6)
Fasting blood glucose (mg/dL)
≤130	11	50	61 (29.5)	0.002
>130	6	140	146 (70.5)
Type of medication for DM
Insulin only	8	80	88 (42.5)	0.97
Oral hypoglycemics only	6	79	85 (41.1)
Insulin with oral hypoglycemics	3	31	34 (16.4)
Median duration since diagnosis of DM (months)	72 (20–103)	72 (36–120)	Median (IQR) = 72 (36–120)

Table 2 Summary of RBC Indices for Patients with Type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023

RBC Indices	Median (IQR)	Maximum	Minimum	Reference Interval
RBC (*10^6)	4.49 (4.24–4.82)	6.29	3.30	4.00–5.50
Hemoglobin (g/dL)	14.2 (13.4–15.3)	18.2	10.0	12.0–17.4
Hematocrit (%)	37.9 (35.5–40.7)	83.2	26.8	36.0–52.0
MCV (fL)	84.6 (81.4–87.1)	122.4	63.5	76.0–96.0
MCH (pg)	31.8 (30.6–32.9)	36.9	21.8	27.0–32.0
MCHC (g/dL)	37.7 (36.7–38.6)	41.0	25.6	30.0–35.0
RDW (%)	13.5 (13.0–14.2)	49.3	12.0	0.0–16.0

Table 3 Mean Difference in RBC Indices Between Those with HbA1C<7 versus HbA1C≥7 Patients with Type 2 DM in Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023

Variables	Mean difference^a	P-value
RBC (*10^6/µL)	1.04	0.141
Hemoglobin (g/dL)	1.08	0.002*
Hematocrit (%)	1.06	0.063
MCV (fL)	1.03	0.138
MCH (pg)	1.04	0.015*
MCHC (g/dL)	1.01	0.332
RDW (%)	0.97	0.424

Notes: ^aValues were back transformed from logarithmically transformed variables. *Statistical significance at P<0.05.

Table 4 Correlation Between HbA1C Level and the RBC Indices Among Patients with Type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023

RBC Indicesa	HbA1C (%)a
	Pearson Correlation (r)	P-value
RBC	0.013	0.851
Hemoglobin	−0.088	0.209
Hematocrit	−0.027	0.705
MCV	−0.086	0.216
MCH	−0.158	0.023*
MCHC	−0.076	0.274
RDW	0.085	0.226

Notes: ^aThe RBC indices and HbA1C were logarithmically transformed to fulfill the assumptions for using Pearson’s correlation. *Statistical significance at P<0.05.

Figure 3 Scatterplot of standardized residual against standardized predicted values.

Table 5 Multiple Regression Analysis for Predictors of HbA1C Among Patients with Type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023

Variable	Unstandardized Coefficients		95%CI for B		P-value	Collinearity Statistics
	B^a	Std Error^a	Lower Bound^a	Upper Bound^a		Tolerance	VIF
Intercept	1.024	0.170	0.689	1.358	<0.0001*
Sex	−0.004	0.014	−0.032	0.024	0.794	0.711	1.407
Age	0.000	0.001	−0.001	0.001	0.704	0.668	1.497
Duration of DM (months)	0.0002	0.000	0.000	0.000	0.587	0.789	1.267
BMI	−0.018	0.008	−0.033	−0.002	0.027*	0.903	1.108
Hypertension history	0.029	0.014	0.001	0.056	0.042*	0.729	1.373
Type of DM treatment	0.017	0.006	0.004	0.030	0.010*	0.783	1.276
Hemoglobin	−0.001	0.005	−0.011	0.009	0.773	0.734	1.363
MCH	−0.008	0.004	−0.015	−0.001	0.033*	0.697	1.435
MCHC	0.001	0.004	−0.006	0.009	0.717	0.701	1.427
RDW	0.004	0.002	−0.001	0.008	0.098	0.761	1.314
FBG	0.001	0.000	0.000	0.001	<0.0001*	0.972	1.029

Notes: ^aValues are for logarithmically transformed dependent variable, Log₁₀HbA1C. *Statistical significance at P<0.05.

Table 6 Diagnostic Performance of RBC Indices to Discriminate Poor Glycemic Control from Good Among Patients with Type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023

	AUC	95%CI	P-value	Cutoff value	Sensitivity	Specificity	PPV	NPV
RBC (*10^6/µL)	0.614	0.544–0.681	0.1180	≤4.57	57.89	70.59	95.65	13.05
Hemoglobin (g/dL)	0.738	0.672–0.796	0.0011*	≤14.8	68.95	82.35	97.77	19.16
Hematocrit (%)	0.689	0.621–0.752	0.0128*	≤41	82.11	58.82	95.70	22.72
MCV (fL)	0.596	0.525–0.663	0.21	≤88.7	86.84	35.29	93.75	19.35
MCH (pg)	0.688	0.621–0.751	0.0103*	≤32.8	77.89	58.82	95.49	19.23
MCHC (g/dL)	0.554	0.484–0.623	0.5175	≤39	90.00	29.41	93.44	20.83
RDW (%)	0.562	0.491–0.631	0.3924	>13.3	58.42	64.71	94.87	12.22

Note: *P-value significant at <0.05.

Figure 4 ROC curve for performance of hemoglobin to assess glycemic control among patients with type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023.

Figure 5 ROC curve for performance of hematocrit to assess glycemic control among patients with type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023.

Figure 6 ROC curve for performance of MCH to assess glycemic control among patients with type 2 DM at Dilla University General Hospital, Dilla, Ethiopia (n=207), 2023.