Analysis of Vitamin B12 Levels in Metformin and PPI Use for Quality Improvement

Metformin and proton pump inhibitors (PPI’s) have been postulated to have an association with vitamin B12 deficiency. In our quality improvement study, we chose to look at patients using metformin and PPI’s. Patients at higher risk also include age over 60, malabsorption disorders such as Crohn’s disease, surgical procedures such as Roux-en-Y, pernicious anemia, elevated mean corpuscular volume (MCV), vegan diets and alcohol use. Metformin interferes with five different pathways of vitamin B12 absorption versus the PPI’s which mainly decrease HCl production, which could explain why metformin presents a greater risk of vitamin B12 deficiency. Though there are no strict designated guidelines for vitamin B12 deficiency screening, consensus agrees that screening is encouraged with long-term metformin use and is not typically recommended for long-term PPI use but can be considered in high-risk patients and if there are symptoms of B12 deficiency. Electronic medical records can be easily accessed to evaluate patients that would qualify for screening, especially older individuals. Early detection of vitamin B12 deficiency is critical as it can lead to subacute combined degeneration which involves the demyelination of neurons in the spinal cord causing irreversible loss of proprioception and fine touch primarily in the lower extremities and ataxia. Treatment of vitamin B12 deficiency through oral, sublingual and intramuscular routes are equally efficacious, however intramuscular B12 is preferred for patients with neurological symptoms.