Objective : The red blood cell distribution width-coefficient of variation (RDW-CV) is a convenient, rapid, low-cost hematological test assessing red blood cell (RBC) size heterogeneity. Besides being significant in hematological disorders, there is emerging evidence of association with cardiovascular and metabolic abnormalities. The chronic inflammation and oxidative stress related to diabetes mellitus and its complications may also lead to anisocytosis, making RDW-CV an easily available biomarker with relevant diagnostic utility.
The objective of our study was to determine the difference in mean RDW-CV among patients with type2 diabetes mellitus and control group and to assess the correlation of RDW-CV with diabetic microvascular complications.
Methods : In a hospital-based observational descriptive study, 100 patients with type 2 diabetes mellitus and 100 healthy controls with normal hemoglobin, hematocrit, MCV, MCHC were evaluated for RDW-CV. Patients with diabetes were further subjected to fundus examination, nerve conduction study, spot urine albumin-creatinine ratio (UACR), blood urea and serum creatinine testing.
Student's t-test for difference in two means, the Pearson correlation coefficient for the correlation between study variables, Kappa statistics for agreement between two diagnostic criteria were used for statistical analysis.
Results : The mean RDW-CV was higher in patients with diabetes as compared to the control group (14.06% and 12.81% respectively, p<0.001) and significantly higher in patients with diabetes having nephropathy as compared to those without nephropathy (15.61% and 13.54% respectively, p<0.001). Though higher RDW-CV was observed in patients with diabetic neuropathy and retinopathy in comparison with those without these complications, the difference was found to be statistically not significant (p=0.0936 and p=0.1234 respectively).
Discussion : Hyperglycemia leads not only to the glycation of hemoglobin but also to other changes in RBCs like decreased deformability and altered mechanical functions. The significantly higher RDW-CV in patients with diabetes in comparison to healthy controls indicates anisocytosis in these patients.
The pathogenesis of nephropathy includes atherogenic macrovascular involvement along with microvascular changes. This could possibly explain the significant correlation of high RDW-CV with nephropathy and no significant correlation with neuropathy and retinopathy.
Conclusion : RDW-CV is higher in patients with diabetes when compared with the healthy population. RDW-CV is increased in patients with diabetic nephropathy and can be considered as a diagnostic marker for prediction of early disease.
SMS Medical College, Jaipur
Jaipur, Rajasthan, India
I am a Professor at SMS Medical College and associated group of Hospitals, Jaipur. I also have a private clinic and work in the specialty of diabetes and endocrinology. I have several papers published in indexed journals and poster presentations. I have also contributed to chapters in books and monographs. I have 20 years of clinical and academic experience.