Frequency of Vitamin B12 Deficiency in Patients With Type 2 Diabetes Mellitus on Tablet Metformin
Keywords:
Type 2 Diabetes Mellitus (T2DM) Metformin therapy Vitamin B12 deficiency Cobalamin deficiency Diabetes complications Neuropathy in diabetes Megaloblastic anemia Glycemic control Long-term metformin use Risk factors (age, duration of therapy, dose) Pakistan / South Asian population Cross-sectional study Prevalence of deficiency Micronutrient monitoring Public health implicationsAbstract
Background: Metformin is first-line therapy for type 2 diabetes mellitus (T2DM) but is known to impair vitamin B12 absorption. Vitamin B12 deficiency can lead to anemia and neuropathy. We assessed the frequency of vitamin B12 deficiency in T2DM patients on metformin in Rawalpindi, Pakistan.
Methods: In this cross-sectional study, 250 consecutive T2DM patients on metformin ≥6 months (age 20–60) were recruited from RMC & Allied Hospitals. Exclusions included type 1 DM, severe organ disease, anemia, recent B12 supplements, or anticonvulsants. Fasting blood sugar (FBS) and serum vitamin B12 were measured. Vitamin B12 deficiency was defined as <200 pmol/L. Data were analyzed using SPSS; continuous variables were expressed as mean±SD and compared by t-test; categorical variables by chi-square test.
Results: The mean (±SD) age was 50±8 years; 52% were male. Mean diabetes duration was 6.2±2.8 years, and mean metformin duration was 4.9±2.6 years. Overall, 15% (n=38) had B12 deficiency (95% CI 11–20%); an additional 22% had borderline levels (200–300 pmol/L). Patients with deficiency were older (mean 55 vs. 49 years, p=0.002) and had longer diabetes duration (7.8 vs. 5.8 years, p=0.004) and metformin duration (7.1 vs. 4.4 years, p=0.001). Gender and BMI were not associated.
Conclusion: In our sample, vitamin B12 deficiency was common in metformin-treated T2DM (15%), with older age and longer metformin use as risk factors. These findings underscore the need for periodic B12 monitoring in long-term metformin users, consistent with international reports of increased deficiency with metformin dose and duration.
