Evaluation of Vitamin B12 Monitoring in Patients on Concomitant Metformin and Proton Pump Inhibitors

Type 2 diabetes mellitus and gastroesophageal reflux disease are highly prevalent in the United States. First-line therapies for these disease states include metformin and proton pump inhibitors, respectively. Both of these medications have been associated with a decreased absorption of vitamin B12.

The objective of this study was to assess the prevalence of B12 monitoring and supplementation in patients receiving concomitant metformin and PPI therapy.

A retrospective data analysis was performed at a single federally qualified health center. Patients receiving concomitant metformin and PPI therapy (specifically omeprazole and pantoprazole) over the past year were included. Data collected included demographics, dosing, therapy duration, and vitamin B12 level. Data were analyzed using descriptive statistics.

A total of 104 patients met the inclusion criteria for this study. Metformin 1000 mg immediate release tablets was the most common dose and formulation prescribed. Omeprazole and pantoprazole were the most commonly prescribed PPIs. The most frequent duration of therapy was 1 to 4 years. Fourteen patients had a documented B12 level and no patients were categorized as deficient. Seven patients were prescribed a B12 supplement during the study period.

In this single center, retrospective chart review of patients receiving concomitant metformin and PPI therapy, the average duration of therapy for both agents was 1-4 years. Only 13.5% of patients had a documented B12 level. Of those patients, none were categorized as deficient. Though routine monitoring of B12 levels may be important for patients on long-term therapy with both agents or who present with symptoms of B12 deficiency, this study does not support routine monitoring of B12 levels for patients with duration of therapy of 4 years or less.