Vitamin B12 Deficiency in the Elderly using Metformin Long Term: Prevalence and Relationship to Putative Risk Factors

Abstract

ABSTRACTAimTo determine the prevalence of vitamin B12 deficiency in elderly patients using metformin long term and to assess putative risk factors for reduced vitamin B12 concentrations.MethodPatients using metformin for more than 2 years admitted to or reviewed in the Repatriation General Hospital from June to December 2006 were enrolled in this cross‐sectional study. The prevalence of vitamin B12 deficiency and the association between vitamin B12 deficiency and putative risk factors were determined.Results60 patients were recruited. Of the 53 patients not taking vitamin B12 supplements, 8 (15%; 95%CI 7.2–28.1) were vitamin B12 deficient (83–148 pmol/L). 7 patients taking vitamin B12 supplements had statistically significantly higher serum vitamin B12 concentrations and decreased B12 deficiency. Daily metformin dose was associated with a statistically significant negative correlation with vitamin B12 concentration and was statistically higher in vitamin B12‐deficient patients. Duration of metformin therapy, age and use of proton pump inhibitors or calcium supplements were not statistically significantly associated with vitamin B12 concentration or deficiency.ConclusionElderly patients taking metformin should be monitored for vitamin B12 status, especially those on high doses of metformin. Vitamin B12, but not calcium, supplements should be considered to prevent or correct deficiency.