Published: 2020-01-23

Correlation of vitamin B12 deficiency with metformin therapy in type 2 diabetes mellitus patients

S. B. Nayyar, Manbir Kaur Dhillon, Sahiba Kukreja


Background: Diabetes mellitus is an endocrine and metabolic disorder, characterized by hyperglycemia. Metformin is the first line pharmacotherapy recommended by ADA. It has been recognized that metformin use is associated with serum vitamin B12 deficiency. The objective of this study is to determine the prevalence of serum vitamin B12 deficiency among Indian patients with type 2 diabetes mellitus on metformin therapy compared to those who are not on metformin.

Methods: Here, 90 patients of type 2 diabetes mellitus of both sexes were included in this cross-sectional study conducted from January 2018 to August 2019 in SGRDIMSR, Sri Amritsar. They were divided into two groups; Group A of 60 subjects of type 2 diabetes mellitus on metformin therapy >1 year and group B of 30 subjects of type 2 diabetes mellitus not on metformin or had stopped taking metformin 6 months back. Serum vitamin B12 levels were measured using a Chemiluminescence method.  Data was statistically analysed.

Results: The serum vitamin B12 levels were 190.02±90.75 pmol/l in group A (metformin users) and 586.9±243.69 pmol/l in group B (not metformin users) (p value=0.002). A significant negative correlation existed between the serum vitamin B12 and duration and dose of metformin use (r꞊ -0.676) and (r -0.855) by using Pearson’s correlation coefficient in group A.

Conclusions: Metformin is associated with decrease in serum vitamin B12 levels. Annual screening of serum vitamin B12 is recommended for patients of type 2 diabetes mellitus who are on metformin therapy for longer duration and /or in higher doses.


Metformin, Type 2 diabetes mellitus, Vitamin B12

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