Endocrine Abstracts

Introduction: Metformin is the only biguanide that is currently in use as an oral hypoglycemic agent in type 2 diabetes mellitus (DM). There are reports about the vitamin B₁₂ deficiency in metformin users. This study was aimed to evaluate the vitamin B₁₂ deficiency in patients with type 2 DM using metformin or other hypoglycemic agents.

Methods: A descriptive-comparative study was performed on 400 patients with type 2 DM presenting to Endocrinology Clinic since Jan 2011 to Jan 2012. The enrolled patients were divided in two groups: i) those receiving metformin from 6 months ago (n=200); and ii) those receiving hypoglycemic agents other than metformin (n=200). Blood samples were taken from all patients after 12 h fasting and serum vitamin B₁₂ and other variables were measured and compared between two groups.

Results: Patients receiving metformin had significantly lower Vitamin B₁₂ levels (320.94±141.34 vs 408.50±175.07 pmol/l, P<0.001) and higher prevalence of vitamin B₁₂ deficiency (14.5 vs 2%, P<0.001). There was negative correlation between vitamin B₁₂ levels with weight (r=−0.18, P<0.001) and BMI (r=−0.11, P=0.02) and positive correlation between vitamin B₁₂ and metformin administration (r=0.26, P<0.001).

Conclusion: Patients with type 2 DM under long-term metformin therapy had lower vitamin B₁₂ levels than those under other hypoglycemic drugs. The relation between vitamin B₁₂ deficiency and metformin therapy indicates the need for periodic measurement of serum vitamin B₁₂ level in patients under long-term metformin therapy.