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Prevalence of vitamin B12 deficiency in type 2 diabetic patients using metformin: a cross-sectional study

Overview of attention for article published in Sao Paulo Medical Journal, June 2016
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Prevalence of vitamin B12 deficiency in type 2 diabetic patients using metformin: a cross-sectional study
Published in
Sao Paulo Medical Journal, June 2016
DOI 10.1590/1516-3180.2015.01382111
Pubmed ID

Charbel Pereira Damião, Amannda Oliveira Rodrigues, Maria Fernanda Miguens Castellar Pinheiro, Rubens Antunes da Cruz Filho, Gilberto Peres Cardoso, Giselle Fernandes Taboada, Giovanna Aparecida Balarini Lima


The prevalence of vitamin B12 deficiency varies from 5.8% to 30% among patients undergoing long-term treatment with metformin. Because of the paucity of data on Brazilian patients, this study aimed to determine the frequency of B12 deficiency and related factors among Brazilian patients with type 2 diabetes mellitus (T2DM) using metformin. Cross-sectional study at a public university hospital. Patients with T2DM and a control group of non-diabetics were included. Serum B12 levels were measured and biochemical B12 deficiency was defined as serum levels < 180 pg/ml. Associations between B12 deficiency and age, duration of T2DM, duration of use and dosage of metformin, and use of proton pump inhibitors (PPIs) or histamine H2 antagonists were determined. 231 T2DM patients using metformin (T2DM-met) and 231 controls were included. No difference in the frequency of PPI or H2-antagonist use was seen between the groups. B12 deficiency was more frequent in the T2DM-met group (22.5% versus 7.4%) and this difference persisted after excluding PPI/H2-antagonist users (17.9% versus 5.6%). The factors that interfered with serum B12 levels were PPI/H2-antagonist use and duration of metformin use ≥ 10 years. Use of PPI/H2-antagonists was associated with B12 deficiency, with an odds ratio of 2.60 (95% confidence interval, 1.34-5.04). Among T2DM patients, treatment with metformin and concomitant use of PPI/H2-antagonists are associated with a higher chance of developing B12 deficiency than among non-diabetics.

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Geographical breakdown

Country Count As %
Unknown 82 100%

Demographic breakdown

Readers by professional status Count As %
Student > Master 12 15%
Student > Bachelor 12 15%
Other 8 10%
Student > Postgraduate 7 9%
Researcher 6 7%
Other 16 20%
Unknown 21 26%
Readers by discipline Count As %
Medicine and Dentistry 33 40%
Pharmacology, Toxicology and Pharmaceutical Science 7 9%
Nursing and Health Professions 5 6%
Agricultural and Biological Sciences 2 2%
Business, Management and Accounting 2 2%
Other 11 13%
Unknown 22 27%