Metformin and vitamin B12 deficiency: A prevalence study

Area of Science:

• Endocrinology
• Metabolic Diseases
• Nutritional Science

Background:

• Current guidelines recommend routine vitamin B12 screening for metformin users.
• These recommendations are based on older, less specific diagnostic criteria for vitamin B12 deficiency.

Purpose of the Study:

• To compare the prevalence of vitamin B12 deficiency in metformin users versus non-users.
• To evaluate the necessity of routine screening using contemporary diagnostic standards.

Main Methods:

• Cross-sectional study of adults with diabetes in Denmark.
• Defined vitamin B12 deficiency using plasma B12 levels and serum methylmalonic acid.
• Used binomial regression to estimate prevalence differences and ratios.

Main Results:

• Vitamin B12 deficiency prevalence was 2.3% in metformin users and 1.3% in non-users (adjusted ratio 1.56).
• In type 2 diabetes patients, prevalence was 2.3% in users and 2.0% in non-users (adjusted ratio 1.21).
• No statistically significant excess risk of deficiency was observed in metformin users.

Conclusions:

• Vitamin B12 deficiency is uncommon among metformin users.
• The excess risk of deficiency in metformin users is not clinically significant.
• Routine biochemical screening for vitamin B12 deficiency in metformin users may be redundant.