Effect of Metformin usage on Vitamin B12 deficiency in patients with Type 2 Diabetes Mellitus

Abstract

Metformin is the most commonly used drug in antihyperglycemic treatment in patients with type 2 diabetes mellitus (T2 DM). In recent years, there have been many studies reporting B12 deficiency in diabetic individuals using metformin drug. This study evaluates B12 deficiency in individuals with T2 DM diagnosis using metformin in our hospital. This study is a cross-sectional and descriptive research. In this study, the data of 786 patients who applied to the Mugla Education and Research Hospital Internal Medicine outpatient clinic with T2DM diagnosis and used metformin between January 01, 2018 and March 01, 2019 were evaluated. Demographic data, vitamin B12, HbA1c levels of the patients were obtained retrospectively from the hospital information system records. Patients with missing data were excluded from the study.347 (44.1%) male and 439 (55.9%) female patients were included in the study. Metformin dose of 248 (31.6%) of the patients was 1000 mg or less, 123 (15.6%) was 1700 mg, 414 (52.8%) was 2000 mg or more. According to the distribution of medication use, 161 (20.5%) patients were receiving metformin only, 322 (41%) patients were receiving metformin + other oral antidiabetic agents (OAD), and 303 (38.5%) patients were receiving metformin + insulin treatment. Vitamin B12 deficiency (57.8%) was higher in patients aged 60 years old and was over who used metformin (p<0.001). 347 (44.1%) of the patients included in the study received vitamin B12 replacement. We detected serious B12 deficiency in patients with T2DM who used metformin, especially in patients aged over 60 years old. Therefore, we emphasize the importance to monitor vitamin B12 levels in patients who are started on metformin and to perform B12 replacement in patients who are found to be deficient.