Red blood cell morphology changes in peripheral blood smear of type 2 diabetes mellitus patients

Background: The prevalence of type 2 diabetes mellitus (T2DM) is rising steadily in Nigeria. Chronic hyperglycemia alters red blood cell (RBC) structure and function, which may contribute to complications. Aim: To evaluate RBC morphology and hematological parameters in patients with T2DM. Methods: A case–control study was conducted at Enugu State University Teaching Hospital from July to November 2024, involving 70 T2DM patients (31 males, 39 females; aged 40–60 years) and 30 age- and sex-matched healthy controls. Hematological indices (RBC count, hemoglobin, packed cell volume [PCV], mean corpuscular indices, red cell distribution width [RDW]) were measured using an automated analyzer. Peripheral blood smears were prepared and examined for morphological abnormalities. Results: T2DM patients had significantly lower PCV (36.89 ± 6.62%) compared with controls (39.55 ± 3.75%, p=0.03). No significant differences were observed in other hematological indices. Peripheral smear examination revealed hypochromasia in 10% of patients and anisocytosis in 6%, with rouleaux formation in one female subject. Increased RDW values were observed in females aged 40–45 years compared with older patients (p<0.05). Conclusion: Patients with T2DM exhibited reduced hematocrit, increased RDW in younger females, and morphological changes including hypochromasia and anisocytosis. These findings support the inclusion of simple, cost-effective hematological parameters in the routine monitoring of diabetes mellitus.