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. 2012 Feb;35(2):327-33.
doi: 10.2337/dc11-1582. Epub 2011 Dec 16.

Association of biochemical B₁₂ deficiency with metformin therapy and vitamin B₁₂ supplements: the National Health and Nutrition Examination Survey, 1999-2006

Lael Reinstatler  1 , Yan Ping Qi, Rebecca S Williamson, Joshua V Garn, Godfrey P Oakley Jr
Affiliations

Association of biochemical B₁₂ deficiency with metformin therapy and vitamin B₁₂ supplements: the National Health and Nutrition Examination Survey, 1999-2006

Lael Reinstatler et al. Diabetes Care. 2012 Feb.

Abstract

Objective: To describe the prevalence of biochemical B(12) deficiency in adults with type 2 diabetes taking metformin compared with those not taking metformin and those without diabetes, and explore whether this relationship is modified by vitamin B(12) supplements.

Research design and methods: Analysis of data on U.S. adults ≥50 years of age with (n = 1,621) or without type 2 diabetes (n = 6,867) from the National Health and Nutrition Examination Survey (NHANES), 1999-2006. Type 2 diabetes was defined as clinical diagnosis after age 30 without initiation of insulin therapy within 1 year. Those with diabetes were classified according to their current metformin use. Biochemical B(12) deficiency was defined as serum B(12) concentrations ≤148 pmol/L and borderline deficiency was defined as >148 to ≤221 pmol/L.

Results: Biochemical B(12) deficiency was present in 5.8% of those with diabetes using metformin compared with 2.4% of those not using metformin (P = 0.0026) and 3.3% of those without diabetes (P = 0.0002). Among those with diabetes, metformin use was associated with biochemical B(12) deficiency (adjusted odds ratio 2.92; 95% CI 1.26-6.78). Consumption of any supplement containing B(12) was not associated with a reduction in the prevalence of biochemical B(12) deficiency among those with diabetes, whereas consumption of any supplement containing B(12) was associated with a two-thirds reduction among those without diabetes.

Conclusions: Metformin therapy is associated with a higher prevalence of biochemical B(12) deficiency. The amount of B(12) recommended by the Institute of Medicine (IOM) (2.4 μg/day) and the amount available in general multivitamins (6 μg) may not be enough to correct this deficiency among those with diabetes.

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Figures

Figure 1
Figure 1
Weighted prevalence of biochemical B12 deficiency and borderline deficiency adjusted for age, race, and sex in U.S. adults ≥50 years of age: NHANES 1999–2006. Black bars are those with type 2 diabetes on metformin, gray bars are those with type 2 diabetes not on metformin, and the white bars are those without diabetes. *P = 0.0002 vs. type 2 diabetes on metformin. †P < 0.0001 vs. type 2 diabetes on metformin. ‡P = 0.0026 vs. type 2 diabetes on metformin.
See this image and copyright information in PMC

References

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