The prevalence of vitamin B12 deficiency in patients with type 2 diabetes mellitus on metformin

The aim of this study is to determine the prevalence of vitamin B12 deficiency among Irish patients with type 2 diabetes mellitus on metformin therapy. We also seek to determine if the dose and duration of metformin use is associated with vitamin B12 deficiency and if the vitamin B12 deficiency is associated with clinical complications. The incidence of type 2 diabetes mellitus in the Irish population is increasing, and it is therefore important to minimise morbidity. Vitamin B12 deficiency is an easily preventable side effect of metformin therapy. It is essential to determine the prevalence of this condition in order to prevent the occurrence of complications, such as peripheral neuropathy and megaloblastic anaemia. Data was collected through the examination of participants’ hospital charts and the use of the electronic database (Patient Information Profile Expander) in Beaumont Hospital, Dublin. This study finds a high prevalence of vitamin B12 deficiency in patients with type 2 diabetes mellitus on metformin therapy. An inverse relationship exists between vitamin B12 levels and the dose and duration of metformin use. Therefore, we suggest that the measurement of vitamin B12 should become an essential part of the annual review in all patients with type 2 diabetes mellitus on metformin therapy.