Journal of Postgraduate Medicine
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Year : 2014  |  Volume : 60  |  Issue : 1  |  Page : 95  

Comment: Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients

VN Shah 
 Barbara Davis Center for Diabetes, University of Colorado, Denver CO, USA

Correspondence Address:
V N Shah
Barbara Davis Center for Diabetes, University of Colorado, Denver CO
USA




How to cite this article:
Shah V N. Comment: Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients.J Postgrad Med 2014;60:95-95


How to cite this URL:
Shah V N. Comment: Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients. J Postgrad Med [serial online] 2014 [cited 2019 Dec 8 ];60:95-95
Available from: http://www.jpgmonline.com/text.asp?2014/60/1/95/128835


Full Text

Sir,

I read the manuscript by Singh AK and colleagues [1] with interest. As the prevalence of type 2 diabetes is increasing in India and metformin is the first-line drug for patients with type 2 diabetes, the number of patients on metformin is also high in India. In addition, as there is no data on metformin use and vitamin B12 deficiency from India, this study is important at present. However, I do have certain concerns about the study, which are as follows:

The authors have stated in the 'Methods' section that, "We did a sample size calculation at 80% power, with an alpha error of 0.05, while taking the expected incidence of B12 deficiency at 25% in the metformin-exposed group and 5% in the non-metformin exposed group based on previous studies" They cited the reference of Reinstatler et al. [2] for this. However, in this same study the prevalence of vitamin B12 deficiency was 5.8% among metformin users. As authors calculated the sample size considering the incidence of vitamin B12 deficiency by 25% in the metfromin group, it would have given a low sample size.The mean level of vitamin B12 in the metformin group, although low, was not sufficiently low to define it as vitamin B12 deficiency. Surprisingly, the vegetarians had higher vitamin B12 than nonvegetarians. Interestingly, although the number of vegetarians using metformin was double that of nonvegetarians using metformin, yet the difference was statistically nonsignificant. Considering that vitamin B12 (although lower in the metformin group) and MCV were normal, it was difficult to explain that the neuropathy in these subjects was a result of vitamin B12 deficiency. It would have been interesting to know whether these subjects recovered with vitamin B12 supplements or not? This would establish the cause and effect relationship between metformin and vitamin B12 deficiency.

References

1Singh AK, Kumar A, Karmakar D, Jha RK. Association of B12 deficiency and clinical neuropathy with metformin use in type 2 diabetes patients. J Postgrad Med 2013;59:253-7.
2Reinstatler L, Qi YP, Williamson RS, Garn JV, Oakley GP Jr. Association of biochemical B12 deficiency with metformin therapy and vitamin B12 supplements: The National Health and Nutrition Examination Survey, 1999-2006. Diabetes Care 2012;35:327-33.

 
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