Evaluation of Vitamin B12 and Homocysteine Status in Patients with Type 2 Diabetes Mellitus without Metformin Therapy

Abstract

Background: Vitamin B12 deficiency and subsequent hyperhomocysteinemia are frequent complications in patients with Type 2 Diabetes Mellitus (T2DM). While these conditions are traditionally associated with long-term metformin use, emerging evidence suggests that metabolic imbalances in cobalamin and homocysteine levels may occur independently of medication ). This study aims to evaluate the status of Vitamin B12 and Hcy in T2DM patients who are not receiving metformin therapy.

Methods: This observational study analyzed clinical and laboratory data from T2DM patients (mean age 55.57 ) who had not used metformin for at least 12 months .Patients with significant renal impairment (Creatinine > 115 µmol/L) were excluded to avoid confounding effects on Hcy excretion. Serum Vitamin B12, plasma Hcy, and HbA1c levels were measured, and statistical correlations were determined using Pearson’s coefficient and ROC analysis.

Results: In the non-metformin group, the mean Hcy level was 12.89- 4.74 µmol/L, which was significantly higher than in the metformin-treated group (11.20- 5.82 µmol/L,) The mean Vitamin B12 level was 370.24 - 211.16 pg/mL . A very strong negative correlation was observed between Vitamin B12 and Hcy levels. Furthermore, Vitamin B12 status showed a significant diagnostic value for predicting hyperhomocysteinemia, with an Area Under the Curve of 0.826. The mean HbA1c level was 11.43 - 2.47%, indicating poor glycemic control in this cohort.

Conclusion: T2DM patients are at risk for B12-related metabolic disturbances even in the absence of metformin therapy. The elevated Hcy levels and their strong correlation with B12 status suggest that factors such as age, disease duration, and glycemic decompensation play a critical role. Regular screening of Vitamin B12 and Hcy is recommended for all T2DM patients to prevent vascular complications, regardless of their pharmacological regimen.