Metformin Therapy and Its Association with Hemoglobin and Vitamin B12 in Type 2 Diabetic Patients

Abstract: Background: Long-term metformin therapy in individuals with type 2 diabetes may influence hematological parameters and vitamin B₁₂ status. This study examines demographic, clinical, hematological, and family-history characteristics in metformin users versus non-users. Methods: Two groups were compared: 38 non-metformin users and 114 metformin users. Variables assessed included gender, age distribution, residence, metformin dosage/duration, side effects, dietary practices, hemoglobin, vitamin B₁₂ levels, and family history of diabetes, heart disease, and B₁₂ deficiency. Results: Both groups had equal gender distribution (50% male/female). Metformin users were older (mean age 56.7 ± 11.4 years vs. 46.2 ± 15.4 years in non-users). A majority of metformin users lived in rural areas (57%), compared to non-users (urban 28.9%). Among metformin users, 58.8% had been on treatment for over 10 years (mean duration 13.3 ± 8.4 years), with a mean daily dose of 720 mg. Most (88.6%) experienced no side effects; gastrointestinal symptoms were reported infrequently. Dietary avoidance of starchy/sugary foods was observed in 25.4%. Hemoglobin was normal in virtually all participants; 7.9% of metformin users exhibited low hemoglobin. Vitamin B₁₂ levels remained largely unknown (97% of metformin users and 100% of non-users), with only 0.9% showing normal B₁₂ and 1.8% low B₁₂ among users. Family history of type 2 diabetes and heart disease was slightly lower in metformin users compared to non-users. Conclusion: Metformin usability typically aligns with older age and rural residence. While hematological indices appear unchanged, unmeasured vitamin B₁₂ levels in the majority signal the need for routine assessment among metformin-treated populations, especially considering external evidence of deficiency risk with prolonged, high-dose use.