ABSTRACT
Background: Due to the clinical benefits of metformin, its associated side
effects such as vitamin B12 deficiency are usually overlooked and rarely
investigated.
Objective: This study was carried out to determine the serum level of vitamin
B12 in Nigerian patients with type 2 diabetes mellitus (T2DM) on metformin.
Methods: Serum vitamin B12 level was determined using high performance
liquid chromatography (HPLC) in 81 T2DM patients who have been on
metformin for 5 years or more. Vitamin B12 deficiency was defined as serum
concentration of >300 pg/dl as normal. Differences in vitamin B12 levels between different
groups were assessed using Mann WhitneyU test andPas statistically significant.
Results: Vitamin B12 deficiency and borderline deficiency were recorded in
8.6% and 26.0% of the patients respectively. Vitamin B12 level was significantly
lower in patients who have been on metformin for >10 years compared with
patients with were on metformin at a dose of >1000 mg/day had significantly lower
vitamin B12 level when compared with patients on Conclusion: Low serum vitamin B12 level is associated with longer duration
and higher dose of metformin use. Therefore, routine determination of
vitamin B12 level in patients with T2DM on high dose of metformin and
those with prolonged use of metformin might help in identifying patients
that would benefit from vitamin B12 supplements.