A study on metformin-induced anemia using red blood cell indices and red cell distribution width

Abstract

Abstract Background: Diabetic patients on metformin may have increased risk of developing anemia. Hematological parameters can easily reflect anisocytosis and differential analysis of anemia. Hence, the study aimed to compare red blood cell (RBC) indices and red cell distribution width (RDW) among metformin and non-metformin users and to determine the association of the RBC indices and RDW with the dosage and duration of metformin. Materials and Methods: This hospital-based observational study comprised 100 type-2 diabetic patients, dichotomized as metformin users and non-metformin users. They underwent face-to-face interview, clinical review, and laboratory investigations focused on hematological parameters and glycemic profile. Results: Participants of the age group of 51-60 years constituted 67% and females comprised 55%. Glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG), and post-prandial blood glucose (PPBG) were significantly higher among metformin users as compared to non-metformin users. Average dosage of metformin was 1281 ± 562.69 mg, and the average duration of metformin usage was 79.84 ± 20.39 months. The mean Metformin Usage Index (MUI) was 8.584 ± 4.4. The metformin users had significantly lower RBC count and higher values for hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and RDW than non-metformin group. Anemia was observed among 50% metformin users and 42% non-metformin users. Normocytic, macrocytic, and microcytic anemia were observed in 69.56%, 21.74%, and 8.7%, respectively, among anemic diabetics. MCV, MCH, and RDW showed a significant positive correlation with MUI. Conclusion: This study revealed anemia in 46% of diabetics, with normocytic anemia being the commonest type, followed by macrocytic and microcytic anemia. Metformin therapy had a significant positive association with MCV and RDW, which was both dose- and duration-dependent. MUI and hematological parameters can be effectively used as a risk assessment for anemia among diabetics on metformin.