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Type 2 diabetes patients may need more vitamin B12

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ATLANTA – According to a study in the December online edition of Diabetes Care, the current recommended daily allowance for vitamin B12 is too low for people taking metformin, an oral drug used to treat diabetes.

Using data from the National Health and Nutritional Examination Survey (NHANES) 1999-2006, researchers from Emory University’s Rollins School of Public Health (RSPH) have found that the Institute of Medicine’s (IOM) current recommendation may be too low for those with type 2 diabetes currently being treated with metformin.

The IOM recommends all adults over the age of 50 consume 2.4 µg of synthetic vitamin B12 daily via supplements or fortified food.

In the NHANES analysis, the weighted prevalence of biochemical B12 deficiency adjusted for age, race, and gender was highest among those with type 2 diabetes taking metformin as compared to those with type 2 diabetes not taking metformin and those without diabetes. Specifically, biochemical B12 deficiency was present in 5.8% of those with diabetes using metformin compared with 2.4% of those not using metformin and 3.3% of those without diabetes.

“It is important to conduct further research to learn how much B12 is needed to correct the deficiency and to determine whether or not raising serum B12 levels improves the clinical picture for persons taking metformin who have low serum B12 concentrations,” says Godfrey Oakley, a RSPH research professor in the department of epidemiology and an author on the study.

Oakley says the findings from this study add to the complexity and importance of vitamin B12 research, especially related to diabetes.  With lifetime risks of diabetes estimated to be one in three and with metformin being a first-line intervention, it is important to better understand the effects of oral vitamin B12 on metformin-associated biochemical deficiency.

In the general population, it has been shown that use of multi-vitamins, which typically contain 6-25 µg of vitamin B12, lowers the prevalence of biochemical B12 deficiency by approximately two-thirds. 

In the Emory analysis, the researchers found that consumption of any supplement containing vitamin B12 was not associated with a reduction in the prevalence of biochemical B12 deficiency among those with diabetes while consumption of any supplement containing B12 was associated with a two-thirds reduction among those without diabetes.

The print version of the study will be available in the February issue of Diabetes Care.

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