Positive Correlation between Microcytosis and HbA1c Levels in Prediabetic Patients in South India: A Comparative Cross-Sectional Study

Abstract

Background: Prediabetes is an intermediate metabolic state whose prevalence is rising rapidly in South India. HbA1c is widely used for diagnosis, but its accuracy may be influenced by haematological factors such as microcytosis, which is common in this region owing to a high burden of iron deficiency. Microcytosis can alter erythrocyte lifespan and glycation dynamics, potentially producing misleading HbA1c values. Objectives: To evaluate the correlation between microcytosis and HbA1c levels in prediabetic patients and to determine whether microcytosis influences HbA1c interpretation. Methods: A comparative cross-sectional observational study was conducted in the Department of General Medicine at Subbaiah Institute of Medical Sciences, Shimoga. Eighty-two participants were divided into two groups of 41 each — one with microcytosis and one with normocytic indices. Inclusion criteria were age 18–60 years, HbA1c 5.7–6.5%, and fasting blood glucose ≤100 mg/dL. Haematological parameters (MCV, MCH, MCHC, RDW), HbA1c, and fasting glucose were compared using SPSS, with p < 0.05 considered significant. Results: Age, gender distribution, BMI, and fasting blood glucose were comparable between groups (p > 0.05). HbA1c was significantly higher in the microcytosis group (6.15 ± 0.23%) than in the normocytic group (5.38 ± 0.18%, p < 0.001). Strong inverse correlations were found between HbA1c and MCV (r = -0.850), haemoglobin (r = -0.715), and MCH (r = -0.801), while RDW correlated positively (r = 0.679), all p < 0.001. Conclusion: Microcytosis is significantly associated with elevated HbA1c independent of glycaemic status. HbA1c may overestimate glycaemic burden in microcytic individuals, supporting cautious interpretation and adjunctive testing in such populations.

Keywords: Prediabetes; Microcytosis; HbA1c; Insulin resistance; Iron deficiency anaemia